White flags have littered streets and adorned homes in besieged Marawi City, where government forces continue to pound on rebels from the Maute group.

This comes as the Armed Forces of the Philippines reminded civilians trapped in heart of the clashes to prepare flags made of white cloth to signal government troops for rescue.

AFP Spokesman Brig. Gen. Restituto Padilla asked residents caught in area of conflict to prepare a white cloth and raise it in able to be recognized and rescued by state forces.

"When you see our soldiers approaching, come out, first women and children with their hands up," Padilla said during the Mindanao Hour in Malacanang.

"When they signal stay in the area where you are, and only move when you are asked to move forward. Once told to move forward, please follow the instruction of our forces."

Padilla estimated, citing figures from the local officials, that about 1,000 residents remain trapped in their houses.

“We hope and pray it’s less because it lessens the complication in the battleground,” he said.

Padilla, meanwhile, said the military continues to vet information that some foreign jihadis were fighting alongside local terrorists. He added he also got reports that some foreign nationals were killed in the clashes, but these information have yet to be confirmed.

“We were able to come across some information, still for confirmation, that indicate that some of those who died are foreigners,” Padilla said.

“[In the] materials coming out and being recovered in the areas of conflict, there could be in this collection of documents proof that would indicate existence of foreign fighters.”

President Rodrigo Duterte placed Mindanao under martial law after government troops clashed with the Maute group and its cohorts in Marawi City.

The clashes erupted as state forces were on their way to arrest Abu Sayyaf leader Isnilon Hapilon, considered one of the most wanted terrorists by the US.

According to Padilla, Hapilon could still be in Marawi City.

-- Reports by Pia Gutierrez, Dharel Placido, ABS-CBN News