Armed bandits have freed 40 people they had abducted from a village in north-western Nigeria's Zamfara state on Saturday, police have said.

The gunmen freed the villagers following the intervention of security agencies and a separate group of bandits who were involved in peace talks with the state government, police spokesman Muhamma Shehu told the BBC.

No ransom was paid, he added.

Bandits have stepped up attacks across north-western Nigeria in recent months, but Saturday's abductions in Zamfara's Mwaru area were on a scale rarely seen.

In the last decade more than 8,000 people have been killed in the states of Kebbi, Sokoto, Niger and Zamfara, according to the International Crisis Group.

The attacks are rooted in decades-long competition over resources between ethnic Fulani herders and farming communities.