Turkish authorities have arrested a man they believe was among the planners of the new year nightclub massacre in Istanbul that killed 39 people, a news agency said.
The private Dogan news agency, citing officials from the prosecutors' office in Burdur, southern Turkey, identified the suspect only by his initials, AS, and said he is a French citizen with an ethnic Turkish background.
He was found with a contract to rent an apartment used by Abdulkadir Masharipov, who carried out the nightclub attack, the agency said.
It said authorities in Burdur had previously issued a warrant for his arrest, but did not provide further details. The man, who had been living in France since 2009, was arrested in Istanbul two days ago.
The Islamic State group has claimed responsibility for the nightclub attack. Masharipov, an Uzbek citizen born in 1983, was caught on January 16 after evading police for more than two weeks.
Last week, he was charged with attempting to overthrow the constitutional order, membership of an armed terror group and murder.
In a related development, prosecutors are demanding that 41 people accused of involvement in an attack at Istanbul's Ataturk International Airport in June be sentenced to several life terms in prison each for attempts to overthrow the constitutional order and premeditated murder, according to an indictment cited by the state-run Anadolu Agency.
The airport attack, which Turkish authorities said was the work of IS extremists, killed 45 people. The three assailants - whom Turkish authorities said came from Uzbekistan, Russia and Kyrgyzstan - were also killed.
The indictment also seeks life imprisonment for three other suspects who are on the run and will be tried in absentia. They have been identified as Nazim Gasanov, Marat Pshnatov and Rustem Efendiev, Anadolu reported.
The indictment needs to be approved by a court before a trial date is set.