MARAWI CITY, Philippines - Philippine aircraft bombed rebel positions and ground troops launched a renewed push against Islamist militants holed up in a southern city on Tuesday, with the aim was to wrap up the fighting before the weekend Eid festival, a spokesman said.

The offensive came amid worry that rebel reinforcements could arrive after Eid al-Fitr, which marks the end of the Muslim holy month of Ramadan.

Fighting in Marawi City has entered a fifth week, and nearly 350 people have been killed, according to an official count. Fleeing residents have said they have seen scores of bodies in the debris of homes destroyed in bombing and cross-fire.

"We are aiming to clear Marawi by the end of Ramadan," said military spokesman Brigadier-General Restituto Padilla, as Army and police commanders met in nearby Cagayan de Oro City to reassess strategy and operations against the militants, who claim allegiance to Islamic State.

• Marawi attackers down to 120, running out of ammo: military

"We cannot definitely say when we could end this because we are fighting door to door and there are booby traps which pose danger to our troops."

The seizure of Marawi has alarmed Southeast Asian nations which fear Islamic State - on a backfoot in Iraq and Syria - is trying to set up a stronghold in the southern Philippines that could threaten the whole region.

Padilla said the military aimed to prevent the conflict from escalating after Ramadan ends.

"We are closely watching certain groups and we hope they will not join the fight," Padilla said.

• Pagbangon ng Marawi, pinaplano na

Some Muslim residents of Marawi said other groups could join the fighting after Ramadan.

"As devout Muslims, we are forbidden to fight during Ramadan so afterwards, there may be new groups coming in," said Faisal Amir, who has stayed on in the city despite the battle.

Fighting was intense early on Tuesday as security forces made a push to drive the militants, entrenched in Marawi's commercial district, south towards a lake on the edge of the city.

Planes flew overhead, dropping bombs while on the ground, automatic gunfire was sustained with occasional blasts from bombs and artillery. Armored vehicles fired volleys of shells while the militants responded with gunfire and rocket-propelled grenades.

An Army corporal near the front line told Reuters soldiers were tagging houses and buildings that had been cleared.

"We still have to clear more than 1,000 structures," he said, adding infantry units were left behind at "cleared" areas to prevent militants from recapturing ground they have lost.

As of Monday, the military said 257 militants, 62 soldiers and 26 civilians had been killed. Hundreds of people are unaccounted for, believed to be hiding in the basements of the city.