Philippine troops clashed with militia forces and arrested more than 60 people in the southern province of Maguindanao. The government has imposed martial law in the region and is pursuing thousands of militia men aligned with the family it says is responsible for the country's worst political massacre.

Presidential press secretary Cerge Remonde said Monday the police fought off an attack late Sunday night in the southern province of Maguindanao.

"According to the military, there were about 30 to 40 rebels that attacked a patrol of the special action force of the Philippines National Police," said Remonde.  "There was a gun battle but there were no casualties to the side of government, but the government had no way of knowing the casualties of the other side, since it happened during darkness. The rebels left after reinforcement arrived."

Thousands of troops, backed by tanks and warplanes, have taken control of Maguindanao province in a crackdown on the powerful Ampatuan clan. The family is accused of orchestrating the November 23rd massacre of 57 people traveling in a convoy. Most were accompanying the wife of a political rival, who was going to register him as a candidate for governor.

Andal Ampatuan, Sr., the provincial governor, and his son Zaldy Ampatuan, governor of the Autonomous Region in Mindanao, which includes Maguindanao, have been taken into custody. They deny any involvement in the crime. Andal Ampatuan, Jr., the mayor of a town in the province, has been charged in the murders.

The Ampatuans have supported President Gloria Macapagal Arroyo but were expelled from her party following the massacre.

The army and police are pursuing about 4,000 armed followers of the Ampatuans. Government negotiators are trying to persuade most of them to surrender peacefully. Remonde says approximately 100 militiamen are suspected of participating in the massacre and will be arrested.

President Arroyo has imposed martial law in Maguindanao. It is the first time martial law has been used in the Philippines since dictator Ferdinand Marcos imposed it nationwide more than 30 years ago.

Pro-democracy advocates accuse Mrs. Arroyo of overreacting. A group of human rights lawyers argues that there are insufficient grounds for martial law and plans to take the issue to the Supreme Court.

Remonde says the president had to take decisive action.

"The people expect leaders to act decisively, take responsibility and do what is right to protect the nation. A nation can ill afford wavering in a time of crisis," he said.

Remonde says once law and order is restored, martial law will be lifted.