MANILA, December 9, 2009 (AFP) - At least 161 people are suspected of having directly participated in a political massacre in the southern Philippines, the nation's police chief said Wednesday.

"We have so far identified 161 suspects who directly participated in the gruesome massacre," Philippines National Police Director General Jesus Verzosa told a nationally televised news briefing.

Police and army officers were among those who carried out the killings of 57 people on November 23 in Maguindanao province, other police chiefs told the briefing.

They said Andal Ampatuan Jr., a local mayor, led the killings to stop a rival politician from registering as a candidate for provincial governor in next year's elections.

Ampatuan Jr. has already been arrested and charged with 25 counts of murder in relation to the massacre.

Giving the most detailed official account of the massacre yet, police said Wednesday 26 of the victims were women and 32 were journalists.

Ampatuan Jr. allegedly abducted the female relatives of a rival politician, plus a group of journalists travelling with them, then shot them dead.

Some of the victims' bodies had been mutilated with knives as well as shot, police said.

Ampatuan Jnr's father, the governor of Maguindanao, and other members of his powerful Muslim clan have also been detained and may face murder charges, police said earlier.

President Gloria Arroyo imposed martial law in Maguindanao on Friday night to quell what the government said was a rebellion by the Ampatuan clan.