ALEOSAN, August 12, 2008 (AFP) - The United Nations has begun airlifting food to the southern Philippines to try to avert a major humanitarian crisis as thousands flee fighting between Muslim rebels and troops, officials said Tuesday.

Fighting continued Tuesday as soldiers used artillery and helicopter gunships to pound rebel positions around towns and villages in North Cotabato, a poor farming region on the southern island of Mindanao.

The UN's World Food Programme has begun airlifting 400 tonnes of rice to communities affected by the conflict, with 160,000 people having fled their homes.

At the same time the Commission on Human Rights and politicians have called for a halt to the fighting to avert a humanitarian crisis.

According to the National Disaster Coordinating Council (NDCC) 43 evacuation centres have been set up for the refugees but they are now 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.

Fighting began 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 Moro Islamic Liberation Front (MILF) rebels take control of mainly Christian villages and towns in North Cotabato province.

They have ignored requests by their leadership to leave.

'The WFP fully understands that the situation remains fluid, and we will continue to work closely with all concerned to further assess the total number of affected persons and adjust our response accordingly,' the UN agency said in a statement issued in Manila.

'WFP remains concerned over the growing number of persons displaced by the violence.

'Many of the affected are women and children, and we are concerned for their wellbeing and stand ready to support humanitarian needs,' it said.

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.'