Cotabatao City, Philippines - Philippine troops clashed with Muslim separatist rebels Friday in a southern province where additional security forces were dispatched to secure areas occupied by the guerrillas, officials said.

The firefight erupted when a group of Moro Islamic Liberation Front (MILF) rebels attacked an army outpost in Midsayap town in North Cotabato province, 930 kilometres south of Manila, said Lieutenant Colonel Julieto Ando, an army spokesman.

Ando said there were no immediate reports of casualties in the fighting, which occurred as additional soldiers and police officers were deployed in the province to ensure that MILF rebels leave communities they had illegally occupied.

Interior Secretary Ronaldo Puno said the MILF leadership has ordered its forces on the ground to "reposition" after the Philippine government gave them 24 hours from Thursday to vacate areas they forcibly took over.

"We need to see this repositioning happen," Puno said. "We need to see the rebels leaving the areas. We will make sure that they vacate the areas."

More than 1,500 families were forced to leave their homes as the MILF rebels took over their communities.

Puno said that once the guerrillas leave, government security forces would take over to allow the displaced residents to return to their homes.

The massing of MILF rebels in North Cotabato came after the Philippine Supreme Court stopped the signing of an agreement that called for the expansion of an existing autonomous Muslim region in the southern region of Mindanao, which includes North Cotabato.

The Philippine government and the MILF were supposed to sign the deal on ancestral domain Tuesday, but Catholic politicians in Mindanao asked the Supreme Court to stop the signing and to nullify the agreement for allegedly violating the constitution.

North Cotabato provincial officials were among the politicians who have voiced strong opposition to the land deal. They have also led street protests in the province against the agreement.

The signing of the ancestral domain deal is a key step in resuming formal peace talks between the government and the MILF, which have been stalled since December.

Aside from expanding the existing six-province Autonomous Region in Muslim Mindanao by holding a plebiscite in more than 700 villages in 2009, the agreement also provides for the establishment of a new form of government for Muslims after a final peace deal is reached.

The 11,000-strong MILF has been fighting for the establishment of an independent Islamic state in Mindanao since 1978. It agreed to hold peace talks with the government in 1997. (dpa)