39 people were killed in the attack at a nightclub in Istanbul.
The mass shooting at an Istanbul nightclub on New Year's Eve was carried out professionally with the involvement of an intelligence organisation, Turkish Deputy Prime Minister Numan Kurtulmus said.
"It appears the Reina attack is not just a terrorist organisation's act, but there was also an intelligence organisation involved. It was an extremely planned and organised act," Kurtulmus was quoted by news agency Reuters.
Turkey has arrested two Chinese nationals of Uighur origin in connection with the attack, news agency AFP reported yesterday.
The suspects, named as Omar Asim and Abuliezi Abuduhamiti, were arrested on charges of "being members of a terrorist organisation", of "purchasing unlicensed firearms" and "being accomplices to the murder of 39 people", state-run Anadolu Agency cited a prosecutor as saying.
A witness in the central Anatolian city of Konya had reportedly seen Asim with the Reina nightclub attacker, the agency said late Friday.
The gunman remains at large despite a massive manhunt.
Officials said last week the attacker was likely a Turkic Uighur, with authorities reportedly looking into the possible existence of a cell, including other terrorists from Central Asia.
Uighurs are Turkic-speaking Muslims from the restive Xinjiang region of far-western China.
ISIS has claimed responsibility for the attack in which 39 people were killed, saying it was revenge for Turkish military involvement in Syria.
(with inputs from Reuters and AFP)