The newspaper said that Celik allegedly arrived in the Turkish city of Izmir from Syria, where he, his friends and Turkmen forces had fought against the country's government.
According to the Hurriyet Daily News, Celik and 13 others were having dinner at a restaurant in Izmir's Hatay district when they were arrested by local police on March 30.
"They were detained after an unidentified person called the police and said there were men with guns in the restaurant," the newspaper said.
Police seized a Kalashnikov assault rifle and two pistols during the detention, Hurriyet Daily News said, adding that the investigation is already under way.
Turkey cracking down on its 'Turkmen rebels'? Alleged killer of Russian pilot and 13 others detained in Izmir: https://t.co/FnJVwbGuXP— Christoph Germann (@newgreatgame) 31 марта 2016 г.
Earlier on Friday, Turkish police confirmed that the alleged killer of the pilot of the downed Russian Su-24 bomber had beened detained.
The Russian Su-24 frontline bomber was shot down by a Turkish F-16 jet over Syria on November 24, 2015 and fell 4 kilometers (2.5 miles) from the Turkish border. The crew of the plane ejected and its pilot was killed by fire from the ground, according to the Russian General Staff. The co-pilot survived.The Su-24's pilot, Lieutenant Colonel Oleg Peshkov, was posthumously awarded a Gold Star medal, Russia's highest award.