Updated 8pm
Eleven people have been arrested after taking part in a riot at the Safi detention centre, in which a police officer was injured and set a fabric tent on fire.
Initially, the police said the cause of the blaze, at around 12.30pm, was unknown, and no one was injured.
As it was burning, the tent produced a thick cloud of black smoke.
Later they said the tent was put on fire and the place was damaged during a riot by a group of irregular migrants.
They said that while the police were providing the necessary assistance, an officer was hit by iron pieces that were being thrown by the migrants and had to be taken to the health centre.
Firefighters from the Civil Protection Department had to be called on site to control the fire.
Video: James Wightman
Photo: Jonathan Borg