Turkey has accused Syria of involvement in the twin attacks in the border town of Reyhanli on May 11, but Damascus has denied any role.
The provincial governor’s office in Hatay Province where Reyhanli is located, said on Tuesday it had detained one of the bombers as he tried to cross into Syria.
“On Monday June 10 at around 23:00, an individual with the initials N.E., who is considered to be one of the main perpetrators of the bombing incidents...was caught near the border in our province’s Yayladagi district,” it said.
Police had been searching for the man. Last month, police detained more than 15 people in relation to the bombings, including another alleged “perpetrator”. Four people have been charged.
Government ministers have said the bombings - among the deadliest attacks in Turkey’s modern history - were carried out by a group with ties to the government of Syrian President Bashar al-Assad.