Turkey has arrested a number of people of Uighur origin over a deadly nightclub attack that killed 39, the state-run news agency reports.
Those detained are believed to have come from China’s Xinjiang region with ties to the attacker, Anadolu says.
Deputy PM Veysi Kaynak also said they were closing in on the gunman, who he said was possibly an ethnic Uighur.
Police have already detained dozens over the deadly new year attack, but the main suspect remains on the run.
So-called Islamic State (IS) says it carried out the attack over Turkey’s military involvement in the Syrian civil war.
The authorities have reportedly tightened security at Turkey’s land borders and airports to prevent the attacker from fleeing the country.
Turkish media have run images of a suspect, saying the pictures were handed out by the police. But the police have given no official details.
The Turkish foreign minister has said the authorities have identified the attacker, but has not given further details.
‘Aiding and abetting’
Special forces made the early morning arrests at a housing complex in Selimpasa, a coastal town on the outskirts of Istanbul, after police were reportedly tipped off that individuals linked to the attacker were in the area.
Uighurs were among those arrested – the number was not confirmed – on suspicion of “aiding and abetting” the gunman, Anadolu reported.
The Uighurs are a Muslim, Turkic-speaking minority in western China, with diaspora communities across central Asia and Turkey.
At least 36 people were already in custody over suspected links to the attack, many of whom were picked up in an earlier police operation in Izmir, western Turkey.
Several families had recently travelled there from Konya, a central city where the main suspect was said to have stayed for several weeks before the attack.