Dozens of people are believed to have been killed in a bombing and gun attack on a mosque in northern Nigeria.

It happened as worshippers gathered for Friday prayers at the central mosque in the city of Kano.

The are understood to have been three blasts next to and in the grounds of the mosque. Gunmen then opened fire on worshippers as they fled.

No-one has claimed responsibility for the attack but it is believed to have been carried out by Boko Haram jihadists, who have targeted the city in the past.