Police have ended an operation in an area of Istanbul that Turkish media reports had said was launched in connection to the Reina nightclub attack that killed 39 people.
Haber Turk television and other media said special operations police, acting on a tip, conducted a raid on an apartment in the Zeytinburnu district late on Monday.
Associated Press journalists at the scene witnessed police leaving the scene without making any arrests.
The private Dogan news agency says the operation was being carried out by special operations police with backing from a helicopter.
The assailant slipped from the scene of the gun attack at the Reina club early on Sunday, taking advantage of the chaos that ensued after he opened fire.
Earlier, Turkey's deputy prime minister Numan Kurtulmus said authorities were close to identifying the gunman after obtaining his fingerprints and a description of his appearance.
Newspaper reports said the attacker was thought to be from a central Asian nation.
The Islamic State (IS) group has claimed responsibility for the attack, describing the gunman as a "heroic soldier of the caliphate who attacked the most famous nightclub where Christians were celebrating their pagan feast".
It said the man opened fire from an automatic rifle and detonated hand grenades in "revenge for God's religion and in response to the orders" of IS leader Abu Bakr al-Baghdadi.