Islamist militant group Ansar Dine has claimed responsibility for an attack on a town in southern Mali in which 21 prisoners were freed from jail, according to a social media posting monitored by the SITE Intelligence Group.

Six attackers tried to release two prisoners from jail in the town of Banamba on Sunday, Mali’s Justice Minister Mamadou Ismael Konate said, but the prisoners had already been moved to another town.

Ansar Dine said in its statement that it had killed one soldier and captured another in the attack and that it had taken three vehicles and some other gear.

Reuters was not immediately able to verify Ansar Dine’s account.

Islamist groups such as Ansar Dine have stepped up their insurgency in Mali this year, carrying out more than 60 attacks on United Nations and other targets since May and spreading south into areas previously deemed safe.

(Reporting by Edward McAllister; Editing by Gareth Jones)