A male lawyer representing the victims also rushed out of the silent courtroom, covering his mouth as he headed for the bathroom to vomit.

However, observers in court said Ampatuan Jnr, who has pleaded not guilty, had displayed no visible reaction to the footage.

No emotion

"He looked bored. It was like the most ordinary thing to watch," Lilian de Lima, head of the government's Commission on Human Rights who was in the courtroom, told reporters.

IN DEPTH


 Profile: Andal Ampatuan Jr
 Witness: 'We just followed orders'

According to prosecutors, at least 10 witnesses have said Ampatuan Jr led 100 of his armed men in the ambush on the convoy on November 23.

Prosecutors allege they then murdered 57 people, including the wife and two sisters of political rival, Esmael Mangudadatu.

The victims were buried in shallow pits or dumped in grasslands just near the national highway in Maguindanao province.

Ampatuan Jr is accused of leading the killings to prevent Mangudadatu from challenging him in the May 2010 race to succeed his father, Andal Ampatuan Sr, as provincial governor.

The family has denied any involvement in the massacre.

Powerful clan

Ampatuan Sr as well as several other clan members were later arrested after martial law was imposed in Maguindanao and charged separately with rebellion.

Ampatuan Jr was said to have shown no emotion while viewing the footage [AFP]
Ampatuan Sr has controlled Maguindanao province for most of the past decade and had been grooming his son to take his place as governor in national elections scheduled for May.

Analysts say Ampatuan Sr's influence and power grew because the government had allowed him to maintain a 3,000-strong heavily armed militia as part of a strategy to contain Muslim separatist insurgents in the south.

In exchange for that support, Ampatuan also helped deliver votes from the province to the Philippine president, Gloria Macapagal Arroyo, and her allies in the 2004 election.

The shocking case forced her to cut political ties with the clan, but critics say the Ampatuans may still hold enough political power to avoid severe penalties.