Yemeni security officials say at least 25 soldiers have been killed in an apparent “friendly fire” incident and battle with militants in the southern province of Abyan.

Local security officials say a government warplane mistakenly bombed an abandoned school where the soldiers were sheltering near the city of Zinjibar on Sunday. They say militants later attacked the school, killing more soldiers.

The apparent friendly fire incident could not be independently confirmed. Yemeni state television denied that a government warplane accidentally killed any troops.

Yemeni security forces have been fighting for months to regain control of Zinjibar and neighboring towns from al Qaida-linked militants who seized the areas in May.