EU interior and justice ministers due to hold a crisis meeting in Brussels
More than 60 people still in a critical condition following the blasts, medical officials say
Two suicide bombers named by prosecutors as brothers Khalid and Brahim el-Bakraoui
Airport blasts killed at least 11 while 20 died in explosion at Maelbeek metro station
So-called Islamic State has said it was behind the attacks
A provisional update sent by the office of Belgian Health Minister Maggie De Block says 31 people are dead and 300 injured, of which 150 remain in hospital.
Brussels airport officials are now saying the earliest resumption of flights could be on Saturday.
Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
Image source, EPABrahim and Khalid el-Bakraoui
The Bakraoui brothers were the latest in a series of siblings to have been involved in terror cells, says Belgian newspaper L'Echo, external.
They follow the Abdeslam brothers who were involved in the Paris attacks last November, the Kouachi brothers who carried out the Charlie Hebdo attacks in January 2015, the Tsarnaev brothers who bombed the Boston marathon in 2013 and Abdelkader Merah, who was charged with helping his brother Mohammed carry out a deadly gun rampage in Toulouse in 2012. The 9/11 attackers also counted sets of brothers among their number.
Former CIA agent Marc Sageman tells L'Echo that it is a "natural phenomenon".
Quote MessageThey grow up together, they grumble and invent an identity as defenders of an Islam that is under threat, of women and children killed in air strikes. They radicalise and validate one another
Quote MessageWhen you need someone to go along with you, the most logical target is your younger or older brother. It's the same with street gangs. There is no need for brainwashing or indoctrination
Psychoanalyst Patrick Amoyel from Nice has worked to deradicalise young people in France.
Quote MessageThey wrap themselves up in a kind of psychological confusion. There is something a little crazy and irrational in these processes. An adolescent form of risk-taking, even if they are no longer adolescents
Mr Amoyel says this "bubble of radicalisation" can grow to include others, for example a best friend who marries the brothers' sister.
Quote MessageAt this level there is a consolidation that is very hard to break. I have seen it very often. And it has nothing to do with mental illness, it is not something psychotic or psycho-pathological
Quote MessageIt goes round and round, one influences the others and vice versa and it can spin out of control. There can be a desire to go beyond the limits towards absolute rebellion. And that can lead to terrorist action
The Belgian authorities are continuing to identify the victims of the bombings. Meanwhile, families and friends are desperately searching for people missing since yesterday's attacks.
David Dixon, a British computer programmer from Nottingham, commutes on the Belgian capital's metro but did not arrive at work yesterday and is missing
Image source, ReutersThe man on the left has been identified in media reports as Najim Laachraoui
French newspaper Le Monde and several Belgian news outlets have identified the second suicide bomber at Zaventem Airport as Najim Laachraoui.
Laachraoui was named earlier in the week by police as a wanted accomplice of Salah Abdeslam.
Analysts say Laachraoui is believed to be a key bomb maker, and French media say he also played a major role in the terror attacks in Paris.
Image source, ReutersThis photo of Najim Laacharoui was released by Belgian police
Image source, EPAPolice raided addresses in the Shaerbeek area of Brussels overnight
A neighbour of the El Bakraoui brothers saw two people carrying heavy bags early on the morning of the attacks, news agency AP reports.
Erdine, 36, who declined to give his last name due to the situation, said he was about to drive his son to school around 07:30 local time when the two people and a cab driver open his trunk.
He said: "The taxi driver tried to get the luggage. And the other guy reached for it like he was saying, 'No, I'll take it'."
Prosecutors say a taxi driver tipped them off to the address in the Schaerbeek neighbourhood of Brussels after the attacks.
Meanwhile, other neighbours expressed shock and bewilderment at what happened.
John Valderrama, who lived across the hall from Khalid and Brahim el-Bakraoui, told AP he never heard anything suspicious.
He said he only saw one person come in or out of the fifth-floor apartment. He was surprised when hours after yesterday's attack, police burst into the brothers' apartment. Police discovered a large cache of TATP explosives there.
Image source, EPAAn Interpol picture of Brahim El Bakraoui, who Turkey says it deported last July
The Turkish presidency has identified the Brussels attacker deported by Turkey last July as Brahim El Bakraoui, who blew himself up at Zaventem Airport.
It follows Turkish President Erdogan's assertion that Turkey had deported one of the Brussels attackers and warned the Belgian authorities he was a militant.
Mr Erdogan said the man was detained at Turkey's border with Syria at Gaziantep
The Turkish presidency said El Bakraoui was later released by the Belgian authorities because they had found "no links with terrorism".
BBC Europe Reporter Gavin Lee writes...
Image source, ReutersThere are still dozens of passengers being escorted out of the Brussels airport security zone, a day on from the biggest terrorist atrocity to hit Belgium. They were guests at the Sheraton Airport hotel.
Security services had advised spending the night at the hotel for their own safety, and intelligence officers have been visiting each room, interviewing guests and looking for anything suspicious. The hotel foyer became the immediate triage area for medical teams, bringing in the casualties and the bodies of those who died.
Now, dozens of military police and soldiers guard the airport entrance, with access only for forensic teams, investigators and airport staff. Several ‘ghost flights’ with no passengers on board set off this afternoon. Airlines are starting to move their aircrafts elsewhere, aware that "business as usual" at Brussels airport could be a long way off.
Image source, AFPKhalid el-Bakraoui, the metro suicide bomber, and brother Brahim, one of the airport bombers
The Belgian authorities were hunting two of the Brussels suicide bombers - brothers Khalid El Bakraoui and Brahim El Bakraoui - before the attacks, an article on The Local's France site suggests., external
An article published last Thursday says police believed a property used by Paris attacks ringleader Abdelhamid Abaaoud was rented by Khalid El Bakraoui.
It describes him as a "convicted car thief, 27, who is at large", and says his brother was "also known to authorities and served a nine-year sentence in 2010 after firing on police during a robbery".
Police searched the property in the southern Belgian city of Charleroi to verify whether the El Bakraoui brothers were there, "though expectations were low as water and electric power had been cut off for weeks", The Local said.
Image source, AFP/GettySpeaking on his visit to Argentina, President Obama has said that defeating the Islamic State group (IS) is his number one priority.
He said that his administration was using all the strategies it could to this end, but that he would not employ tactics that were counterproductive.
Mr Obama said it was wrong to think that carpet-bombing Syria or Iraq would help, as it would be inhumane and would help IS attract new recruits.
He also said it would be wrong to discriminate against Muslim communities in America, which he said were well-integrated and patriotic.
He said:
Quote MessageI’ve got a lot of things on my plate. But my top priority is to defeat ISIL and to eliminate the scourge of this barbaric terrorism that’s been taking place around the world.
Quote MessageWe see high profile attacks taking place in Europe, but they’re also killing Muslims throughout the Middle East. People who are innocent, people who are guilty only of worshiping Islam in a different way than this organisation.
Quote MessageThey are poisoning the minds of young people everywhere. Not just in Europe but in the US and undoubtedly in Argentina people are looking at these websites. So there is no more important item on my agenda than going after them and defeating them."
One of the Brussels attackers was deported from Turkey last July, Turkish President Recep Tayyip Erdogan has said.
Turkey reported the deportation to the Belgian authorities, who later set him free, Mr Erdogan said.
The Belgians ignored Turkey's warning that the attacker was a militant, the Turkish president added.
Israeli newspaper Haaretz claims, external it has learned that the Belgian security services, as well as other Western intelligence agencies, had "advanced and precise intelligence warnings" about planned attacks in Brussels.
Intelligence services knew "with a high degree of certainty" that attacks were planned in the very near future for the airport and, apparently, for the underground railway as well, the newspaper claims.
Haaretz says the attacks were planned in Raqqa, the Islamic State (IS) group's headquarters in Syria. It says the IS cell that attacked Brussels was linked to the cell responsible for the attacks in Paris last November.
The report also says the Brussels attacks were triggered by the arrest of Salah Abdeslam because the jihadists feared he would reveal details of the plans.
More Belgians have gone to fight for so-called Islamic State than any other European country - but why?
Read More
The Prime Minister of Poland, Beata Szydlo, has said her country will no longer take in migrants after the Brussels attacks.
Reuters reports that Ms Szydlo told TV station Superstacja:
Quote MessageTwenty-eight EU countries agreed to solve the issue through relocation. But I will say it very clearly: I do not see it possible to allow migrants in Poland at the moment."
Mark Toner, Deputy Spokesperson: for the US State Department, says about a dozen Americans were injured in Tuesday's attacks.
He said the US authorities were not aware of any Americans among the victims, but said a number of US citizens remained unaccounted for.
They include some staff members at the US embassy in Brussels, Mr Toner said.
The embassy is served by the Arts-Lois metro station, a neighbouring station to Maelbeek, where the explosion on the metro train happened.
The Belgian authorities have not yet released nationality information for the reported deaths, Mr Toner added.
Image source, Getty
Image source, Getty
Image source, Getty
Image source, AFPLondon will pay tribute to victims using major landmarks this evening.
Mayor of London Boris Johnson said Londoners would show "solidarity with the people of Brussels"
Tributes have been left outside the Belgian Embassy in London
The BBC's Anna Holligan has spoken to the parents of siblings who are still missing after the attacks.
Their father said he was on the phone to them when the explosion happened.
"It sounded like they fell into a ditch," he said.
Image source, Evan Lamos via APMobile phone footage showed people evacuating another metro train near Maelbeek
Belgian state broadcaster RTBF says it has spoken to the driver of the bombed metro train, external at Maelbeek station.
Christian Delhasse said at first he thought there had been a technical problem, but he soon he realised it was much more serious. He stopped the train immediately, and began to help victims.
He told the broadcaster: "I did what I had to do. I had nothing, no injuries. I immediately complied with the procedures, it is all I can say."
Seeing the bodies of victims on the ground had left him shocked, he said.
The attack in the subway station left 20 dead and hundreds injured.
Mr Delhasse was back driving trains on Wednesday, the Brussels transport authorities said.