SHARIFF AGUAK, Philippines, December 8, 2009 (AFP) - Military aircraft on Tuesday dropped leaflets over a southern Philippine province that is under martial law urging members of a warlord's militia force to surrender.

"These are persuasion flights," said Colonel Leo Ferrer, an army commander whose forces are hunting down about 3,000 militiamen loyal to the Ampatuan clan in the province of Maguindanao.

Thousands of leaflets were dropped from two helicopter gunships that circled remote hilly areas where the militiamen are believed to have entrenched themselves, he said.

Two OV-10 Bronco bomber planes were also sent to fly over the areas to drive home the message of superior military might, Ferrer said.

The leaflets contained messages in the local dialect calling on the militiamen to "surrender for the sake of peace in Maguindanao", according to Ferrer.

"There is also a telephone number to call if they wish to surrender. And the leaflets will serve as their safe conduct passes if they wish to do so," he said.

The government placed Maguindanao under martial law on Friday, citing a rebellion by members of the Ampatuan clan and its heavily armed militiamen.

Clan members are accused of masterminding the political massacre of 57 people last month, a crime police said was meant to stop a member from a rival clan from pursuing the Maguindanao governorship in elections next year.

The clan chief, Andal Ampatuan Sr., had been governor of the province and an ally of President Gloria Arroyo's government since 2001. But the government arrested him after the massacre and declared him an enemy of the state.