COTABATO, Philippines: The International Committee of the Red Cross (ICRC) Saturday called on the Philippines military and Muslim rebels not to stop aid reaching civilians displaced by fighting in the south of the country.

The organisation's deputy director, Dominik Stillhart, made his appeal after saying he had heard reports that a UN World Food Programme convoy carrying aid to the area had been stolen.

He called on the army and Moro Islamic Liberation Front (MILF) to respect international laws protecting non-combatants amid the violence in southern Mindanao island, which he said was at its worst for five years.

"They must take all possible steps to spare civilians from the effects of hostilities and must allow and facilitate the deliveries of emergency relief and medical supplies to all who need them," said Stillhart.

"The ICRC is stepping up its operation in the region over the coming months. We intend to provide assistance and protection for up to 350,000 people between now and the end of the year."

He would not elaborate on whether this meant the ICRC expected the fighting to last that long but said the increased aid was needed because "the conflict here is extremely violent."

"Up to half a million people have been displaced by the hostilities and tens of thousands of them have had to flee their homes," he said.

There have been accusations that the MILF had hijacked a food shipment in the town of Mamaspano on Wednesday, while the government has been forced to dismiss accusations that soldiers were blocking food from reaching civilians.

The fighting between government troops and MILF guerrillas broke out in Mindanao last month after the Supreme Court suspended a draft agreement on August 4 intended to pave the way for a formal peace accord.

"Mindanao has suffered its worst fighting since 2003," Stillhart told reporters, saying that the ICRC had to bring in additional staff to deal with the increased number of civilians displaced by the combat.

Conditions for the civilians were difficult, he said, especially since it rains almost every night in the south, forcing people to crowd into the small schoolrooms that are doubling as evacuation centres.

He recalled stories of people fleeing in the night, amid heavy rain, with one mother forced to wrap her baby in plastic to protect the child.

ICRC officials refused to speculate on whether there might be more evacuations, especially if fighting steps up following the Muslim holy month of Ramadan.

"We do not know what will happen after Ramadan," said ICRC delegate Perry Proellochs but he expressed hope that some of the evacuees could return.

The government's civil defence office said Saturday that 501,709 people had been displaced by the violence, with at least 67 dead, although military estimates put the death toll much higher.

The 12,000-strong MILF has been fighting for a separate Islamic state since 1978. In 2003 it signed a ceasefire with Manila to open the way for peace talks.

- AFP/yt