MANILA, Philippines (AP) - Communist rebels ambushed a Philippine army platoon south of Manila on Saturday, killing at least 11 soldiers and wounding seven others in one of the military's largest recent losses, an army spokesman said.

About 60 New People's Army guerrillas who ambushed the soldiers outside Mansalay township in Mindoro Oriental province also are thought to have suffered casualties, said Lt. Col. Noel Detoyato, spokesman for the army's 2nd Infantry Division.

The three-hour battle ended when army reinforcements arrived and the guerrillas withdraw, Detoyato said. Troops were pursuing the rebels, he said.

It was the biggest loss for the army in a single encounter with the rebels this year. Last month, rebels killed five soldiers and wounded eight others in a clash in a mountain village in the northern Philippines.

Troops have been deployed to the area of Saturday's ambush, about 150 miles (240 kilometers) south of Manila, to prevent the rebels from extorting money from candidates to allow them to campaign in May elections, Detoyato said.

The military says the rebels have collected millions of pesos (tens of thousands of dollars) in "permit to campaign" and "permit to win" fees from candidates running for local and national positions.

In a statement last week, the Communist Party of the Philippines denounced the military's allegations as "dirty psywar attacks." It said the permits were "guidelines" to ensure that campaigns "do not violate the people's rights and interests, and are conducted in an orderly and peaceful manner" in guerrilla zones.

The rebels have about 4,000 fighters, down from a peak of about 25,000 in the mid-1980s, according to military estimates.

They have been waging a 41-year rural-based insurgency that has triggered human rights abuses and stunted economic development.

President Gloria Macapagal Arroyohas ordered the military to crush the insurgency by the end of her term in June, but the rebels have dismissed the deadline.

Peace talks between the rebels and the government brokered by Norway collapsed in 2004 after the guerrillas blamed the Philippine government for their inclusion on U.S. and European lists of terrorist groups.

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