United States Special Forces are providing support to the Philippine military battling to dislodge militants in a southern city as 13 Filipino marines were killed in fresh fighting.

Philippine troops are struggling to defeat hundreds of fighters, who rampaged through Marawi on May 23 flying black flags of the Islamic State group, and have used bomb-proof tunnels, anti-tank weapons and civilians as human shields to fortify their positions.

Friday’s ferocious, street-to-street Gunbattles with the militants saw 13 troops killed in a dramatic surge in the toll from the conflict.

As the fighting intensified, the US embassy in manila said American forces were providing assistance to the Filipino troops, although it declined to give details for security reasons.