Turkey's state-run news agency says authorities have arrested two more people with suspected links to the suicide bomber who killed 10 Germans in Istanbul, raising the number of arrests to 12.

Anadolu Agency said the two were detained in the city of Sanliurfa, bordering Syria, on Saturday. A court in Istanbul has charged them with premeditated murder and membership in a terror group on Wednesday.

Ten Syrians were charged with membership in a terror group and ordered jailed on Sunday.

The suicide bomber set off the explosion near a group of German tourists on Jan. 12, just steps away from the landmark Blue Mosque. Turkish officials say the Syrian bomber was affiliated with the Islamic State group. No group has claimed the attack.