More than 60 women and girls are reported to have escaped from the Nigerian Islamist group Boko Haram, BBC has reported, quoting security sources.

They were among 68 abducted last month near the town of Damboa in north-eastern Borno state.

Reports say the women escaped when the militants went to attack a military base near Damboa on Friday.

The Nigerian military said it killed more than 50 rebels in a clash that night.

Boko Haram is still holding more than 200 schoolgirls abducted in April.

Local vigilante Abbas Gava told journalists he had “received an alert from my colleagues... that about 63 of the abducted women and girls had made it back home.”

“They took the bold step when their abductors moved out to carry out an operation,” he said.

A high-level security source in the state capital Maiduguri confirmed the escape, AFP news agency reported.

Boko Haram triggered an international outcry when it captured 200 girls in Borno’s Chibok town on April 14.

It is demanding the release of its fighters and their relatives in exchange for the girls but the government has rejected this.

A state of emergency is in force in three northern Nigerian states (Borno, Yobe and Adamawa) because of Boko Haram’s increasingly violent campaign to overthrow the government and create an Islamic state.

Maiduguri was the headquarters of Boko Haram until it was forced out by the military and vigilante groups.

•Adapted from a BBC report. Photo shows some of the abducted Chibok schoolgirls who earlier escaped from Boko Haram’s grip. Over 200 of them remain captive.