Although opposition legislators questioned government officials for hours on the legality of the move, the vote was largely a foregone conclusion as Duterte enjoys majorities in both houses of Congress.
The authorities in the Philippines have hit the rebels' logistics hard, cutting off key supplies and seizing large amounts of weapons and explosives.
A military spokesman said the deadline to completely free Marawi of armed elements cannot be met because militants had taken civilians as hostages, using women and children as human shields.
The violence that began last week has killed dozens. Though most people have left, those still trapped are worried about being intercepted by militants at checkpoints on routes out of the city.
Subscribe to our Youtube channel for all latest in-depth, on the ground reporting from around the world.
Copyright © 2021 TRT World.