Gunmen in Nigeria have freed nearly 200 prisoners from a jail, officials say.

Hadijha Aminu, from the Nigerian Prisons Service, told the BBC the jail in Koton-Karifi in the central state of Kogi was attacked on Wednesday evening.

She said a large number of men with weapons stormed the prison, but details of the attack were still unclear.

Ms Aminu declined to explain why the involvement of the Islamists had been ruled out and said most of the freed inmates were awaiting trial.

Boko Haram, whose name means "Western education is forbidden", wants to establish Islamic law in Nigeria.

http://www.bbc.co.uk/news/world-africa-17059895