Multiple explosions hit a refugee camp in northeastern Nigeria, killing at least four people and injuring 18 others. The camp offers shelter to people fleeing Islamist militants Boko Haram.

The explosions hit the Muna Garage camp area around 4.30am (3.30am GMT), the police commissioner of the city of Maiduguri Damian Chukwu told Reuters on 22 March.

Chukwu added that two of the explosions happened at the camp, which shelters internally displaced people fleeing the Islamist militants, who seek to establish an Islamic caliphate in northeastern Nigeria.

The number of the explosions is contested, as the coordinator of the Muna camp Tijjani Lumani told AFP there were four explosions – suicide bombs – inside the camp.

"The explosions triggered fires which burned down many tents," he added.

Unicef Nigeria wrote a statement on Twitter expressing "deep concern for people impacted by explosions overnight". According to The Office for the Coordination of Humanitarian Affairs in Nigeria (OCHA), the camp hosts "tens of thousands" of internally displaced people.

This is the latest in a string of attacks in the Maiduguri area, one of the worst affected by the violence, where bombings on Sunday 19 March killed four people.

A man claiming to be Boko Haram's leader appeared in a video released on 17 March claiming responsibility for bombings in the city.