GENERAL SANTOS, Philippines, December 3, 2009 (AFP) - The Philippine army on Thursday sent hundreds of extra troops to contain a powerful Muslim clan whose members have been indicted for the political massacre of 57 people last week.

The extra battalion of 400 soldiers brings to more than 3,000 the number now guarding the home of the Ampatuan clan and government offices in Maguindanao province, military spokesman Lieutenant Colonel Romeo Brawner said.

"Our forces are now stationed in the area. They are restricting their movement within the compound (home)," Brawner told AFP. "We have added one more infantry battalion."

Supporters of the clan, which has ruled Maguindanao for a decade and has its own private army, were being barred from entering the home in the provincial capital of Sharrif Aguak, Brawner said.

The move is also meant to support the national police if and when warrants of arrest are issued for several clan members who could be charged with murder, including the patriarch Andal Ampatuan Sr., he said.

"Right now the security is very tight in the area. We are stopping their supporters from entering their home," Brawner said.

The patriarch's son and namesake, Andal Ampatuan Jr., was arrested three days after the November 23 massacre and has been charged with 25 counts of murder so far. Authorities said he will likely face more charges.

The savagery of the murders, which included the deliberate targeting and execution of at least 30 journalists, has shocked this Catholic nation as well as the international community.

Police have indicted Ampatuan Sr. and four other family members for their alleged role in the massacre, and are waiting for the justice department to decide whether to charge them in court.

Police allege Ampatuan Jr. and 100 of his gunmen shot dead the occupants of a convoy that included relatives of his rival for the post of Maguindanao governor in next year's elections, as well as a group of journalists.

The rival, Esmael Mangudadatu, said the killings were carried out to stop him from running for office.

Many of the journalists killed were from General Santos, a major port city a few hours' drive from where the massacre took place.

Ampatuan Jr. and Sr. were members of President Gloria Arroyo's ruling coalition until being expelled last week because of the killings.