Turkish Police on Wednesday detained at least five suspected Islamic State group militants believed to be linked to the deadly Istanbul nightclub attack, Turkey's state-run news agency reported.
Anadolu Agency said the operation was launched in the Aegean port city of Izmir and was under way as reported last.
The gunman, who killed 39 people, including two Indians, during New Year's celebrations, has not been publicly named and is still at large.
The IS group has claimed responsibility for the attack, which also wounded nearly 70 people.
The private Dogan news agency said the police operation targeted three families who had arrived in Izmir about 20 days ago from Konya a city in central Turkey where the gunman is thought to have been based before carrying out the nightclub attack. It said 27 people, including women and children, were taken into custody.
At least 14 people were previously detained in connection with the attack, including two foreigners stopped Tuesday at the international terminal of Istanbul's Ataturk Airport after police checked their cell phones and luggage, according to Anadolu.