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.

Image source, EPA

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".

Psychoanalyst Patrick Amoyel from Nice has worked to deradicalise young people in France.

Mr Amoyel says this "bubble of radicalisation" can grow to include others, for example a best friend who marries the brothers' sister.

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.

Image source, Reuters

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, Reuters

Image source, EPA

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, EPA

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".

Image source, Reuters

There 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, AFP

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/Getty

Speaking 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:

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?

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:

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.

London will pay tribute to victims using major landmarks this evening.

• Two Belgian flags will be projected onto the front of The National Gallery 
• London Eye, Tower Bridge and The National Theatre will display the colours of the Belgian flag

• Trafalgar Square fountains will run the colours of the Belgian flag
• A 25m silk flag will be placed on the central staircase in Trafalgar Square ahead of a vigil organised in partnership with the Belgian Embassy between 18:00 and 22:00 GMT. People can also leave flowers and candles
• Many government buildings in the capital are already flying the Union flag and the Belgian flag at half-mast

Mayor of London Boris Johnson said Londoners would show "solidarity with the people of Brussels"

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 AP

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.