The Interior Ministry said police raided 30 locations and arrested 47 people as part of the investigation into the attack.
ADVERTISEMENTIn a statement released late on Sunday, the Islamic State group claimed responsibility for an attack on a Roman Catholic church in Istanbul during Sunday Mass that left one person dead. The incident is still under investigation by the Turkish authorities.
The extremist group said it "attacked a gathering of Christian infidels during their polytheistic ceremony" at the Santa Maria church in Istanbul's Buyukdere neighbourhood on Sunday.
Two people with their faces covered entered the church and opened fire on one person, who did not survive the attack.
Interior Minister Ali Yerlikaya said shortly before midnight that two men he described as members of the Islamic State extremist movement had been arrested for the attack. One of the suspects is from Tajikistan, the other from Russia. Dozens of suspects were later arrested, the minister said.
The claim of responsibility was posted on Aamaq, the militant group's media arm, along with photos of two masked men with guns whom it identified as the attackers. The group said it was "in response to calls by Islamic State leaders to attack Jews and Christians everywhere".
It described the attack as killing one person and wounding another, while Turkish authorities said no one was injured apart from the dead.
Yerlikaya said police had raided 30 locations and detained a total of 47 people as part of the investigation into the attack.
However, investigators have doubts about whether this was a terrorist attack directly linked to the group or whether the jihadist organisation claimed responsibility for the incident.
"We will never tolerate those who try to disturb the peace of our country - terrorists, their collaborators, national and international criminal groups and those who target our unity and solidarity," Yerlikaya said.
The man who was killed has already been identified by the police.
He was Tuncer Cihan, 52, of Turkish nationality. Turkish media have quoted his relatives as saying that Cihan was not involved in politics and suffered from a "slight mental disability".
On 3 January, 25 suspected Islamic State members were arrested across Turkey and accused of planning to attack churches and synagogues, according to the state-run Anadolu Agency.
Islamic State has not previously targeted places of worship in Turkey, but the militant group has carried out several deadly attacks in the country, including a 2017 shooting at an Istanbul nightclub that killed 39 people and a 2015 bombing in Ankara that killed 109 people.