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The BBC News website will continue to follow events closely as Turkey hunts the gunman who killed dozens of people celebrating the new year in Istanbul. And below you can find some related material:

Eyewitnesses describe the horror

The glamorous Reina nightclub 

Gunman caught on camera

The US is denying reports in Turkey that it knew in advance of a possible terror threat to a nightclub in Istanbul.

"‎Contrary to to rumors circulating in social media, the US Government had no information about threats to specific entertainment venues, including the Reina Club," the US Embassy in Ankara said in a statement. 

It said the US had issued a "general holiday season threat warning for Turkey and various parts of Europe" on 22 December, but did not warn Americans to stay away from specific venues or neighbourhoods. 

BBC Monitoring
News from around the globe

Murat Karayilan, an executive council member of the banned Kurdistan Workers' Party (PKK), has reportedly said that no Kurdish forces were involved in the attack.

Kurdish forces would "never target innocent civilians", the pro-PKK Firat News Agency quoted him as telling a Kurdish radio station.

He said he doubted that the TAK - a militant PKK offshoot responsible for several recent attacks in Turkey- would carry out such an attack.

Who are the PKK?

Prime Minister Benali Yildirim's office has released this picture of him (R) visiting the hospital bed of a man who survived last night's attack.

Image source, Prime Minister's press office

Metin Gurcan, an Istanbul based security analyst, told the BBC that it is proving difficult for Turkey to deal with fighting the two fights it is currently engaged in.

He says: "First one is the fight against PKK, the secular leftist Kurdish anti-nationalist armed group, now a state actor.

"And the second fight is the fight against so-called Islamic State (IS). 

"How can you allocate resources and capacity? 

"This is, I think, the grave question the decision makers right now in Turkey have been asking. 

"Which one of these should be prioritised, the fight against the PKK or the fight against IS?"

Because the people who died were mainly civilians, the finger of blame for this attack is being pointed at IS. But the motive for the attack is not yet clear and the gunman has not been apprehended.

Of the 39 people confirmed killed, at least 15 are known to be foreign nationals.

There are victims from Lebanon, Jordan, France, Tunisia, Israel, Belgium and Saudi Arabia, reports say.

Here is what we know about them at this point:

• Three are Jordanians, the foreign ministry says.
• Saudi nationals are reported to have been killed but the numbers vary
• The family of Elias Wardini, a Lebanese national, say they have been informed of his death. At least one more Lebanese citizen is reported to have died
• A French-Tunisian dual national died, the French foreign ministry confirms
• Tunisia's foreign ministry said on Facebook that two Tunisians died. It is unclear if either of them is the French-Tunisian dual national
• An 18-year-old Israeli woman was killed, the government said. Leanne Nasser was celebrating with three friends at the Reina nightclub
• Belgium's foreign ministry confirmed a Belgian-Turkish dual national died

French Foreign Minister Jean-Marc Ayrault has confirmed the death of a French-Tunisian dual national. 

A ministry spokesman tweeted the news:

Image source, Flickr: Aylamillerntor (Creative Commons)

The site of Turkey's latest deadly attack is a glamorous nightclub on the shores of the Bosphorus.

Celebrities are often spotted there, and it's also a favourite among international visitors.

One tourist from London described it in dreamy terms: "You can just sit there and watch all the beautiful people of the city".  

Read more:

Where the young and beautiful party

Prime Minister Yildirim confirmed that more than 60 people were injured, and said three or four of them were in a critical condition. 

At least 39 people are known to have died.

Image source, Prime Minister's Press Office

The prime minister has rejected earlier reports that the assailant was dressed in a Santa Claus outfit.

"This is not true," he said.

Turkish Prime Minister Binali Yildirim says the nightclub attacker left his gun at the scene before fleeing.

A TV station in Lebanon is reporting that one of the dead from last night's attack was a Lebanese citizen.

Elias Wardini was missing. His family have spoken to New TV and say they have been officially informed of his death.

Riot police are guarding the Reina nightclub in Istanbul.

Image source, Reuters

After Turkey's latest deadly attack, Turkish Prime Minister Binali Yildirim says that the country will not be cowed.

"The most important, the biggest assurance for us, is the spirit of solidarity our nation is displaying before all these attacks," he told journalists.

"There is no problem we cannot overcome."

BBC Monitoring
News from around the globe

Israeli Prime Minister Benjamin Netanyahu has condemned the Istanbul attack and called for concerted international efforts to fight terrorism, The Jerusalem Post reports, external. 

Speaking at the opening of Sunday's cabinet meeting Mr Netanyahu quoted Chancellor Merkel's remarks over the weekend that "the biggest threat to the future of the world is from extremist Islamic terror," the paper reports.

One Israeli woman is known to have died in last night's attack. Another was wounded.

The funerals of some of the victims of the attack have begun already, quickly as is the norm under Muslim tradition.

Image source, Reuters

Today is the World Day of Peace in the Roman Catholic calendar. 

It's the 50th anniversary of the tradition and Pope Francis had prepared a message about meeting violence with non-violence.

He departed from his prepared speech to acknowledge the attack that started the new year.

He said: "Unfortunately, violence has stricken even in this night of good wishes and hope. 

"Pained, I express my closeness to the Turkish people. I pray for the many victims and for the wounded and for the entire nation in mourning."

Image source, AFP