Gunmen free over 1,800 from Nigerian prison

Gunmen have freed more than 1,800 inmates from a prison in southeastern Nigeria.

That's according to the prisons authority, which said rocket propelled grenades, machine guns, explosives and rifles were used in the attack.

Nigerian police believe a banned separatist group, the Indigenous People of Biafra, was behind the attack.

A spokesperson for the IPOB denied involvement.

The prison assault in the city of Owerri took place in the early hours of Monday (April 5) morning, a Nigerian Correctional Service spokesman said.

Explosives were used to blast the administrative block of the prison and enter the prison yard, according to a police statement.

Tensions have been increasing in southeastern Nigeria in recent months.

A paramilitary wing of the IPOB, known as the Eastern Security Network, has been accused of involvement in clashes with the military.

Several police stations have also been attacked since January.

Large amounts of ammunition have been stolen, though no group has claimed responsibility.

For the government of President Muhammadu Buhari, it's just one of several major security challenges across the country including an Islamist insurgency in the northeast, school kidnappings in the northwest and piracy in the Gulf of Guinea.