Turkey has accused Syria of involvement in the two bombings last weekend in the town of Reyhanli, which fanned fears that Syria's civil war is dragging in neighbouring states. Damascus denies any role.

Local governor Celalettin Lekesiz said police had detained a man identified only by the initials M.G. shortly before midnight on Thursday in Samandag district, near the Syrian border, and that he was being treated as a prime suspect.

Huseyin Celik, deputy chairman of Turkey's ruling AK Party, said the two vehicles used in the bombings were registered to the man who was detained, and that he had driven one of them to one of the blast sites in Reyhanli.

Lekesiz said police were still searching for two other suspected perpetrators, who along with M.G. had been trying to cross over into Syria from Samandag but had failed because of stepped-up security along the border.

He said the two men were believed to be still inside Turkey.

A total of 16 people were in detention in relation to the bombings, Lekesiz said, four of whom had been formally arrested. It was not clear what charges they faced.

Interior Minister Muammer Guler has said the bombings - one of the deadliest attacks in Turkey's modern history - were carried out by a group with direct links to Syrian intelligence.

Foreign Minister Ahmet Davutoglu has said the perpetrators were from an "old Marxist terrorist organization" with ties to the government of Syrian President Bashar al-Assad.