The Islamic State group has claimed responsibility for the New Year's Day mass shooting in a packed Istanbul nightclub that killed 39 people, an attack carried out by a lone gunman who remains at large.
The jihadist group described the Reina nightclub, where many foreigners as well as Turks were killed, as a gathering point for Christians celebrating their "apostate holiday". The attack, it said, was revenge for Turkish military involvement in Syria.
"The apostate Turkish government should know that the blood of Muslims shed with airplanes and artillery fire will, with God's permission, ignite a fire in their own land," the Islamic State declaration said.
"This attack is a message to Turkey against its decisive operations across the border," Turkish government spokesman Numan Kurtulmus said.
The authorities are close to fully identifying the gunman, Kurtulmus said, after gathering fingerprints and information on his basic appearance, and had detained eight other people.
Nationals of Saudi Arabia, Lebanon, Morocco, Libya, Israel, India, Canada, a Turkish-Belgian dual citizen and a Franco-Tunisian woman were among those killed at the nightclub.
All of those killed died from gunshot wounds, some of them shot at a very close distance or even point-blank range, according to a forensics report quoted by Milliyet newspaper.
Police distributed a hazy black-and-white photo of the alleged gunman taken from security footage.
The authorities believe the attacker may be from a Central Asian nation and suspect he had links to Islamic State, the Hurriyet newspaper said. It said he may be from the same cell responsible for a gun-and-bomb attack on Istanbul's main airport in June, in which 45 people were killed and hundreds wounded.
The attack at Reina, popular with Turkish celebrities and wealthy visitors, shook Turkey as it tries to recover from a failed July coup and a series of deadly bombings, some blamed on Islamic State, others claimed by Kurdish militants.
Around 600 people were thought to be inside when the gunman shot dead a policeman and civilian at the door, forcing his way in then opening fire with an automatic assault rifle. Witnesses said he shouted "Allahu Akbar" (God is Greatest).
Witnesses described how he shot the wounded as they lay on the ground.
The attacker was believed to have taken a taxi to the nightclub then pulled his Kalashnikov rifle from a suitcase at the side of the road, opening fire on those at the door, then throwing two hand grenades after entering.