Cairo: An Egyptian coalition of rights groups said on Tuesday that police arrested at least 237 people during the previous day’s protests in Cairo against a government decision to hand over to Saudi Arabia control of two strategic Red Sea islands.

Rights lawyers Gamal Eid and Mohammad Abdul Aziz — both members of the Front for the Defence of Egyptian Protesters — said that all those detained were in custody by midnight on Monday when the front made its last tally.

The number of those still held could be lower since police have been intermittently releasing the detainees, they said. It’s unclear if anyone has been referred to prosecutors.

Thousands of police were deployed across much of Cairo on Monday to stifle plans for mass demonstrations called to protest the government’s decision to surrender the islands of Tiran and Sanafir.