An Mao, 31, told the Supreme Court he had prepared thousands to take part in an attack on key government buildings in Phnom Penh last November 24.
"When we planned the fight we thought we could win, but only 50 people turned up," An Mao said, drawing laughter from court spectators.
"At the beginning I had 3,000, then I had 500, then only 50. I ordered (all CFF members) to fight, but they did not listen to me," he said on the third day of a high-profile trial of 32 people charged with terrorism and forming an armed group.
Despite the poor turnout, An Mao said he led the small group on an attack of the ministry of defense and military barracks on the outskirts of the capital.
After one hour of shooting, An Mao told his men to go home.
The Freedom Fighters is an anti-communist group based in Long Beach, Calif., that claimed responsibility for armed attacks on three government buildings on Nov. 24.
At least four of the attackers were killed during the fighting, and dozens of police and other officials were wounded.
"I was sorry for those who lost their life. When I saw our people could not succeed, I ordered them to drop their weapons. Now I have only sorrow in my life," he said.
An Mao said he was arrested on his way home when he identified himself to police he mistook for fellow rebels.
Meanwhile, defense lawyers who walked out of the court hearing on Monday saying the court was not independent of the government ended their boycott on Wednesday morning after receiving letters from Judge Sok Sithamony requesting their attendance.
The 29 Cambodians and three U.S. citizens are being tried on charges that they formed and armed group and then carried out a terrorist act. They face up to 20 years in prison if convicted. Two of the U.S. citizens are being tried in absentia.
An Mao has admitted responsibility for leading the attack but the defendants have not yet been asked formally to plead.
The hearing was set to resume on Thursday.
Authorities arrested another suspect in the attacks Monday night. Court officials must decide whether to formally charge Duong Sopheap, a 28-year-old customs department official.
Critics of the government, including opposition leader Sam Rainsy, have accused it of instigating the violence, which provided a pretext for the intimidation of people working for nonviolent change. Security officials deny those allegations.
According to a Web site apparently run by the CFF, the group's mission "is to stop a nightmare of massacre, violence, crime against humanity, and help enforce the bills passed by the United States Congress and United Nations to bring the Genocidal Leaders to the world court of justice."
"CFF has not recognized and wll not recognize the current government who was born out of an election fraud and brutality, (and) gave immunity to the former Khmer Rouge Leaders who were responsible for the deaths of two million Cambodians instead of bringing them to justice," the Web site reads.
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