Turkish authorities have formally arrested 25 suspects in connection with the shooting of a man during a service at a church in Istanbul last weekend, Justice Minister Yilmaz Tunc said on Friday.

Among the 25 remanded in custody were the two suspected gunmen, previously captured by police, who are believed to be tied to Islamic State, Tunc said on the social media platform X.

The two main suspects were foreign nationals, one from Tajikistan and the other Russian, Interior Minister Ali Yerlikaya said previously.

Islamic State claimed responsibility for the attack in a statement on Telegram, saying it was in response to a call by the group's leaders to target Jews and Christians.

Tunc said the 25 suspects were charged with membership of an illegal organisation and aggravated intentional homicide, adding that another nine suspects were released pending trial.

The attack took place on Sunday morning at the Italian Santa Maria Catholic Church in Istanbul's Sariyer district. One Turkish citizen - who was targeted by the gunmen - was killed while attending the service.

The murdered man had gone into the church while out for a walk and had no political or religious affiliations, his cousin has said. Authorities have said the attack could have been deadlier if not for a jammed weapon.

CCTV footage from the inside of the church, verified by Reuters, showed the masked gunmen entering the building and shooting the man who was walking in front of them.

Islamic State has conducted numerous attacks across Turkey, including on a nightclub in Istanbul on Jan. 1, 2017, in which 39 people were killed.

Turkish authorities have detained 2,086 people suspected of ties to Islamic State since June 2023, Yerlikaya has said.