MANILA : The Philippines has sent 1,000 troops to guard food aid in its troubled south, officials said Friday, as the Red Cross warned of a "humanitarian crisis" after a surge in separatist violence and the halting of a peace process.

Two infantry battalions were redeployed to Mindanao island in the past few days, said military spokesman Brigadier-General Jorge Segovia.

He said they would help in the relief effort amid reports that armed men have disrupted the supply of emergency food rations to hundreds of thousands of civilians displaced by a flare-up in the conflict.

A hardline faction of the separatist group Moro Islamic Liberation Front (MILF) raided Christian villages across the island last month, leaving scores of civilians dead and displacing around 280,000.

This week, President Gloria Arroyo scrapped a government peace panel seeking to end the drawn-out rebellion in a major policy shift.

A Manila spokeswoman for the United Nations World Food Programme said one of its food aid convoys was stopped near the town of Mamasapano on Wednesday by armed men who stole 28 bags of rice.

The report came as International Committee of the Red Cross country chief Felipe Donoso voiced fears displacements could rise to crisis levels as food stocks run out.

With fighting "appearing to continue and the security situation remaining volatile, it is likely that tens of thousands of families will be displaced over the coming weeks," Donoso warned in an interview posted on the agency's website.

"To avoid a humanitarian crisis, the ICRC plans to distribute food rations to 325,000 persons over the next four months," he added.

Segovia said the authorities were checking reports that MILF rebels had been stopping food convoys, while warning that military checkpoints would prevent aid workers from entering areas where their safety could not be ensured.

The MILF meanwhile said it is honouring a three-year-old ceasefire and that it remains committed to pursuing peace negotiations with President Arroyo's government.

However, it rejected her demand to disarm before talks can resume.

"We continue to uphold the Peace Path as still the best way forward to address the centuries-old Bangsamoro Problem in Mindanao," MILF vice-chairman Ghazali Jaafar said in a statement.

Mindanao, the homeland of a 4.5 million-strong Islamic minority that has seen bouts of separatist rebellion in the past 40 years, has been "relatively peaceful" this week, Segovia said.

The lull, which followed the start of the Muslim fasting month of Ramadan, was disturbed only by the small-scale harassment of military units.

The government Friday doubled to 10 million pesos (about 213,000 dollars) the bounty on each of the two MILF rebels accused of leading last month's attacks, Ameril Umbrakato and Abdurahman Macapaar, police said.

MILF deputy chief Jaafar said "abuses" committed by both sides should be investigated by a "non-partisan organisation recognized by the Parties."

He also urged the UN to step up aid to the displaced Mindanao residents, whose scale he said has reached "the level of (a) humanitarian crisis."

The MILF attacks followed a Supreme Court writ issued last month against a draft peace agreement proposing extended powers to a Muslim self-rule area that would be led by the 12,000-member MILF.

- AFP /ls