Police named 100 government militiamen as additional suspects in the Philippines' worst political massacre Wednesday as prosecutors filed rebellion charges against a powerful clan accused of ordering the brutal attack on a rival's campaign convoy.
President Gloria Macapagal Arroyo's top Cabinet officials appeared before lawmakers to defend her proclamation of martial law in southern Maguindanao province, where 57 people were killed, some left sprawled on the ground and others buried in mass graves.
Critics called the martial law declaration a dangerous precedent, but Cabinet members said it was needed to stave off a rebellion by the Ampatuan family, the main suspects in the Nov. 23 killings, and their thousands-strong private armies ready to fight the government.
The Ampatuan clan gained notoriety for intimidating political opponents and protecting their turf, which until the massacre made any action against them impossible.
The head of the Philippines' independent Commission on Human Rights, Leila de Lima, said her office had received a letter from anonymous citizens blaming the Ampatuans for at least 200 other killings in the area in the past decade. De Lima cautioned that the allegations had not been validated and did not provide details but said she would investigate.
She said her office had asked the elder Ampatuan to comment on the allegations but he never responded.
Witnesses in custody have identified Andal Ampatuan Jr., a scion of the clan, as leader of a group of government militiamen who attacked a rival's convoy in Ampatuan township, said national police chief Jesus Verzosa.
The dead included 30 journalists and their staff.
According to the witnesses, Ampatuan himself shot some of the victims. The bodies bore bullet wounds in the mouth and chest fired from close range, Verzosa said.
Police said the bodies of some of the 21 female victims were mutilated, including their sexual organs. Authorities earlier had said at least five women may have been raped.
Among the total of 161 murder suspects are about 100 newly identified militiamen, only two of them in custody _ Esmael Kanapa and Takpan Dilon of the Civilian Volunteer Organization, a police auxiliary force, police officials said Wednesday.
Government-sponsored militias have become a fixture in many Philippine provinces plagued by Muslim and communist rebellions and by bandits. Over the years, the over-stretched military and police have been arming civilian volunteers as a back-up force. In areas like Maguindanao, some have become de facto private armies on the payroll of local political warlords.
The remainder of the newly named murder suspects are members of the Ampatuan clan or are police, army and local officials working for the Ampatuans. About 30 have been arrested.
Ampatuan Jr., a town mayor and the only one charged with multiple murder so far, turned himself in three days after the killings and denied involvement. His father _ family patriarch Andal Ampatuan Sr. _ four brothers and 19 others who were arrested on rebellion charges after Arroyo signed martial law Friday were separately indicted.
They were still undergoing preliminary investigation on murder charges, Justice Secretary Agnes Devanadera told lawmakers.
Arroyo's declaration of martial law _ the first use of military rule in the Philippines since late dictator Ferdinand Marcos imposed it nationwide more than 30 years ago _ has raised concerns that it was an overreaction made on shaky legal grounds.
Congressmen and senators adjourned a vote on martial law until Thursday. Despite heated debate, Arroyo's allies dominate the lower house and were expected to endorse it.
Prosecutors filed the rebellion charges Wednesday in Cotabato city, the regional trial court is closest to the massacre site, but said they would seek the transfer to Manila.
Some congressmen and legal experts worried charging them with rebellion might muddle the murder charges because rebellion is a political offense, not a criminal one.
Executive Secretary Eduardo Ermita and top police and military commanders insisted the danger was real _ security forces have recovered combat vehicles, police cars, scores of weapons and about half a million ammunition rounds in and near properties of the clan.
A Justice Department statement Wednesday cited witnesses and investigators as saying the elder Ampatuan Sr. had ordered his private armies to "fight the government to death" if members of his clan and other supporters were arrested.
Heavily armed loyalists _ most of them militiamen _ fled to mountain villages to hide, ready to attack in case the Ampatuans were rounded up, the statement added.
Arroyo's martial law order allowed government forces to arrest suspects without waiting for court warrants and to move against some 2,400 armed Ampatuan loyalists.
Troops were instructed to shoot them on sight after the gunmen ignored thousands of air-dropped leaflets urging them to give up peacefully, said military commander Maj. Gen. Anthony Alcantara.
Ampatuan Sr., a three-term governor of Maguindanao, has ruled the impoverished lawless province for years while his sons and relatives held positions in towns named after them.
He had forged a political alliance with Arroyo since 2001, and his province delivered crucial votes for her in the 2004 presidential elections. Her ruling party expelled the Ampatuans after the massacre.
Associated Press writers Teresa Cerojano, Jim Gomez and Oliver Teves contributed to this report.