Taliban militants have attacked a police base in northern Afghanistan, killing or wounding 25 police officers and kidnapping 31, officials say.

The raid took place late on Monday in Faryab province, where Taliban and Islamic State militants are fighting government forces.

The attackers were reportedly armed with machine guns and used artillery.

The fighting lasted for five hours and both sides had heavy casualties, a local Afghan commander told the BBC.

The Taliban launched what the group calls its spring offensive in early April.

Afghanistan has seen a surge in attacks in recent months, with militants often targeting state security forces.

A recent BBC study found that the Taliban now control or threaten much more territory than when foreign combat troops left in 2014.

Taliban fighters are openly active in 70% of Afghanistan, the study found.