At least 30 people have been killed in a suicide attack in north-eastern Nigeria, officials say.

Another 40 have been injured, according to the State Emergency Management Agency.

The bombers detonated their explosives outside a hall in Konduga, Borno State, where football fans were watching a match on television.

Jihadist group Boko Haram is being blamed for the attack, though it has not claimed responsibility for it.

It has frequently carried out bomb attacks in the state.