MANILA- No way in, no way out.

This is the goal of the Armed Forces of the Philippines (AFP) as it speeds up clearing operations in besieged Marawi City, its Chief of Staff General Eduardo Año said Tuesday.

"That's our main goal, no way out, no way in. They want to join... they want to go to heaven, sabi nila, so we will give them the chance to go to heaven"," Año told reporters.

The military chief said fighting in the Islamic city, which has entered its fourth month, has been contained within less than 500 square meters, but that troops are expecting tougher firefights with the remaining Islamic State-linked Maute extremists.

"We will expect fierce confrontations with Maute-ISIS as they do their last stand," he said.

Año believes the Maute leaders, brothers Omar and Abdullah, are still alive and within the battle area.

"As far as we know, Abdullah and Omar are still there. Yes, they are still there," he said.

The military chief refused to set a deadline as to when the military could resolve the crisis.

Año, however, made the assurance that the military is ready to go after terrorists who would attempt to reinforce remaining Maute extremists holed up in the city or those who would try to escape.

"Gusto lang nating ipakita dito na anywhere they go, if they will attempt to reinforce, or they will escape, they (soldiers) are ready to get them," he said.

A total of 792 people, mostly terror suspects, have died since clashes erupted between state forces and Islamic State-inspired extremists on May 23.

The clashes have forced more than 200,000 out of Marawi City and thousands more from nearby areas. The crisis has also destroyed much of the once bustling urban center.

• READ: Marawi terrorists mount 'last stand', child warriors join battlefield: military