MANILA, Philippines?Twenty-three suspected gunmen loyal to the Ampatuan clan accused of an election-linked massacre have surrendered and turned in their weapons, President Gloria Macapagal-Arroyo's spokesman said Friday.

Cerge Remonde said the men were likely part of the 3,000-member private army of the Ampatuan family, which is accused of mounting an armed rebellion in the southern province of Maguindanao following the massacre of 57 people on November 23.

Arroyo imposed martial rule in the province on Friday last week.

The gunmen were detained in Rajah Buayan town on Thursday after military and police units tasked with enforcing martial law seized more firearms from the home of the detained clan patriarch, Andal Ampatuan Sr., Remonde said.

"Later in the day, 23 renegade CVO (civilian volunteer organization) members in Rajah Buayan surrendered and turned in their weapons. They are now being processed for possible filing of appropriate cases against them," he said.

The CVO is a volunteer force of police aides whose members help the regular forces fight local insurgencies.

But the government alleges the Ampatuan clan illegally armed these volunteers and used them to intimidate their political rivals.

The victims of the November 23 mass murder included relatives of Buluan town Vice Mayor Ishmael "Toto" Mangudadatu, a rival politician who was set to contest the governor's post in next year's elections against the patriarch's son and namesake, Datu Unsay Mayor Andal Ampatuan Jr.

The son has been arrested and charged with multiple murder, accused of ordering more than 100 bodyguards to abduct and then kill the victims.

Amapatuan Sr. had been the governor of Maguindanao since 2001, but was detained in the martial law sweep and will soon be charged with rebellion.

He and his family were allowed to build up their own armies as part of a government strategy to contain a long-running Muslim separatist insurgency in Maguindanao and other parts of the southern Philippines.