A group that tracks online extremist activity says Boko Haram claims to have killed "seven apostates" in an attack on a military barracks in southeast Niger.

SITE Intelligence Group said the Nigeria-based group took credit for the attack in the town of Ghafam in the Diffa region in a statement Friday.

The statement said Boko Haram fighters also took "weapons and various ammunition."

More than 20 soldiers were killed earlier this month during clashes with Boko Haram in southeast Niger, and the U.N. refugee agency said last week that more than 50,000 people had been forced to flee as a result of the recent fighting.

Boko Haram's nearly seven-year-old insurgency has killed some 20,000 people and forced 2 million from their homes.