Cotabato City, Philippines - A Philippine Army officer was wounded Wednesday in fresh clashes with Muslim secessionist rebels in the country's south, where 102 people have been killed and nearly 150,000 displaced since last week, a military report said.

The fighting erupted when patrolling soldiers encountered about 30 heavily armed Moro Islamic Liberation Front (MILF) rebels in Shariff Aguak town in Maguindanao province, 930 kilometres south of Manila.

Fighting was ongoing and soldiers were using mortars and howitzers to flush out the rebels, the military report said.

The military has launched a manhunt for two senior MILF commanders - Ameril Umbra Kato and Abdullah Macapaar, alias Commander Bravo - who are accused of leading the spate of attacks in six provinces in the southern region of Mindanao.

Interior Secretary Ronaldo Puno said the government was offering 5 million pesos (109,890 dollars) for information that would lead to the arrest of Kato and Bravo.

Major Armand Rico, a regional military spokesman, said authorities were verifying reports that Kato was seriously wounded in an attack by unidentified gunmen late Tuesday in Kabuntalan town in Maguindanao.

Kato led hundreds of MILF guerrillas in occupying villages in North Cotabato province last week, which resulted in fierce clashes with government forces that displaced more than 104,000 residents at the height of the hostilities.

Rico said Kato, along with two bodyguards, were allegedly ambushed late Tuesday by unidentified armed men in Kabuntalan.

"As per our report, he was seriously wounded," he said. "His men carried him as they escaped."

Commander Bravo, who has been blamed for a series of attacks in the adjacent provinces of Lanao del Sur and Lanao del Norte since Sunday, has denied the allegations lodged against him.

"We don't know who led that group," he said. "We have no plans to sow terror in Mindanao. It is the government of the Philippines that is creating trouble in Mindanao."

The escalation of attacks by MILF guerrillas started shortly after the Supreme Court stopped the signing of a land deal between the MILF and the government that would have expanded an existing autonomous Muslim region in Mindanao.

Catholic politicians have alleged that the deal violated the constitution and would have ceded sovereignty over the southern Philippines to the Muslim rebels. They urged the high tribunal to declare the deal unconstitutional.

The military and police have placed forces on red alert in Mindanao and Manila amid intelligence reports that MILF guerrillas might launch more attacks.