The authorities in Nigeria say 13 policemen were killed in an ambush by suspected armed gangs in the north-western state of Zamfara on Sunday.

Seven others were also wounded after they responded to distress calls from villagers in the Bungudu local government area of the state.

A statement by the governor of Zamfara state, Bello Matawalle, said the police officers “came under fire following an ambush staged by armed gangs”.

The incident comes a day after armed assailants kidnapped at least 50 people from several villages in the wider state, which has been riven by insecurity.

Cases of armed gangs attacking communities and kidnapping villagers - many of them for ransom - have risen.

In other parts of Nigeria, attacks on security agents by gunmen have also been on the rise.

Last week, an army general was killed by suspected armed gangs near the capital Abuja.

On the same day four soldiers were also killed at different locations across the country.