ALEOSAN, August 12, 2008 (AFP) - Muslim rebels have begun withdrawing from positions in the southern Philippines after days of heavy fighting as relief agencies ferry in food to avert a humanitarian crisis among the thousands who have fled the violence, officials said Tuesday.

Security forces said Moro Islamic Liberation Front (MILF) rebels had began withdrawing from villages and towns in North Cotabato province on the southern island of Mindanao mid morning Tuesday, torching property and planting mines.

Pikit police chief Inspector Elias Dandan told AFP the rebels burned buildings including a church in the town and planted land mines and booby-traps as they retreated.

'An elderly couple and their adult son were killed by the rebels,' he said.

The story was much the same in other areas of the province as the MILF rebels left burning houses and crops in their wake.

The military said at least 27 rebels were killed and nine wounded with one soldier dead and 12 wounded.

Regional police chief Superintendent Felizardo Serapio said:' 'operations are over. We are just clearing up.

'Houses have been razed and scattered gun fire and mortar shelling is still going on as the rebels retreat,' he said.

The UN's World Food Programme began shipping 400 tonnes of rice from warehouses in Cotabato City to communities affected by the conflict, with 160,000 people having fled their homes.

According to the National Disaster Coordinating Council (NDCC) 43 evacuation centres have been set up for the refugees but they were overcrowded and fast becoming health hazards.

'This is turning into a humanitarian mess,' congresswoman Risa Hontiveros said Tuesday.

'The refugee crisis is an unacceptable cost of the government's mismanagement of the peace process. A peace process should lead to the protection of life and property, and yet what's happening is the opposite,' said Hontiveros, who has called for an immediate halt to the fighting.

Violence erupted last week after the Supreme Court ordered the government to suspend plans to establish an extended Muslim homeland in the southern Philippines.

The decision saw around 1,500 heavily armed renegade MILF rebels take control of mainly Christian villages and towns in North Cotabato province.

Sporadic machine gun fire could be heard as the rebels withdrew from positions they had occupied since last week having ignored earlier requests by their leadership to leave.

'The UN World Food Programme is gravely concerned about the humanitarian situation in North Cotabato province,' Stephen Anderson, the WFP's country director in Manila told AFP.

'It is essential that appropriate relief supplies are despatched urgently and distributed to the affected populations most of whom are now in evacuation centres, which are overflowing,' he said.

He said some of the refugees had been living in the centres since June when they were displaced by Typhoon Frank which caused widespread destruction throughout the Philippines.

About 40 WFP staff were the immediate vicinity of the conflict zone coordinating relief efforts with the NDCC.

Commission on Human Rights chairwoman Leila de Lima described the situation in North Cotabato as 'serious' and called for an immediate ceasefire.

She told local television that evacuation centres needed urgent supplies of food and medicines for the refugees.

Dozens of civilians, mainly women and children, continued to flee the fighting Tuesday carrying whatever they could.

The government has said that the fighting will not disrupt the ongoing peace process and that the Supreme Court decision last week was a 'temporary setback.'