Manhunt after dozens killed in Istanbul Nightclub attack

The sisters of Elias Wardini, a Lebanese man confirmed killed, mourn his death (AP)

Police in Istanbul are hunting for a gunman who opened fire at a well-known nightclub, killing at least 39 people.

The attack happened at Reina nightclub early on Sunday, as hundreds of revellers marked the new year.

Officials say some 15 foreigners were killed, including citizens from Israel, France, Tunisia, Lebanon, India, Belgium, Jordan and Saudi Arabia.

The attacker left his gun before "taking advantage of the chaos" and fleeing the scene, Turkey's PM said.

Binali Yildirim also confirmed the gunman was not dressed as Santa Claus, contradicting earlier reports.

The attack unfolded some 75 minutes into the new year as around 700 people gathered in the waterside Reina club, one of Istanbul's most upmarket venues.

The attacker shot dead a policeman and a security guard at the entrance before heading into the club, which is popular with celebrities and foreigners.

Eyewitnesses described seeing dozens of bodies lying on the floor. Some revellers reportedly threw themselves into the Bosphorus to escape the carnage.

"Gunshots rang out. When those sounds were heard, many girls fainted," professional footballer Sefa Boydas told AFP news agency.

He said people appeared to be crushed as they ran away. "They say 35 to 40 died but it's probably more because when I was walking, people were walking on top of people."

Relatives of the victims gathered outside Istanbul's forensic medical centre waiting for news (AP)

At least 69 people are being treated in hospital, officials said, with three in a serious condition.

The motive for the attack is not clear, but suspicion has fallen on the Islamic State group.

President Recep Tayyip Erdogan blamed terror groups "trying to create chaos". "They are trying to... demoralise our people and destabilise our country," he said.

The banned Kurdistan Workers' Party (PKK) said it was not the work of Kurdish groups. They would "never target innocent civilians", the PKK's Murat Karayilan was quoted as saying.

Details of those who died are starting to emerge.

The security guard at the entrance to the club has been identified as Fatih Cakmak.

His brother said he narrowly escaped a double bombing three weeks ago, having been on duty when Kurdish militants launched an attack near a football stadium, killing at least 44 people, mostly police.

Here is what we know of the other deaths:

• Israel has confirmed Leanne Nasser, 19, was killed while out celebrating with three friends
• Three Jordanians are among the dead, Jordan's foreign ministry says
• The family of Lebanese national Elias Wardini say they have been informed of his death. At least one more Lebanese citizen has reportedly died
• A French-Tunisian dual national has died, the French foreign ministry confirms
• Tunisia's foreign ministry said on Facebook that two Tunisians died. It is not clear if one of those includes the French-Tunisian dual national
• Belgium's foreign ministry confirms a Belgian-Turkish dual national has died
• India's foreign minister Sushma Swaraj tweets confirmation of the death of two nationals

US President Barack Obama, who is on holiday in Hawaii, offered condolences "for the innocent lives lost" and offered "appropriate assistance".

Reina nightclub, seen here in a file picture, is one of the most exclusive in Istanbul (Reuters)

Russian President Vladimir Putin condemned the "cynical" murder of civilians. "Our shared duty is to decisively rebuff terrorist aggression," he said.

Turkey and Russia are working together on efforts to end the fighting in Syria, though they support different sides in the conflict.

Istanbul was already on high alert with some 17,000 police officers on duty in the city, following a string of terror attacks in recent months.

BBC contributed to this report