A family accused of massacring 57 people for political gain in the Philippines plotted the killings over dinner, a court has heard.

Servant Lakmudin Saliao gave evidence on the first day of the trial of the Ampatuan clan saying its head Andal Ampatuan Sr gathered his relatives to ask them how they could stop a rival from running for provincial governor.

Former town mayor Andal Ampatuan Jr replied: "That's easy. If they come here just kill them all,'" Mr Saliao told the court.

He said the elder Ampatuan then asked his children if they agreed with the plan, and "Everybody laughed, saying it's OK for everybody to be killed."

The trial nearly 10 months after the November 23 massacre in southern Maguindanao province exposed the shocking violence of Philippine politics. Among the 57 dead were 30 media workers travelling in an election convoy.

Mr Saliao said Ampatuan Sr ordered that his rival, Esmael Mangudadatu, must be stopped on a road where he was supposed to pass on the way to file his candidacy papers.

On a nearby hilltop troops found the 57 bodies gunned down and hastily buried along with some of the victims' vehicles in mass graves.

Mangudadatu, who was later elected governor in the May elections, had sent his wife, sisters and other female relatives accompanied by journalists in the belief that their lives would be spared.

On the day of the murders, Mr Saliao said Ampatuan Jr told his father via mobile phone that he had blocked the convoy. The father ordered him to gun down everybody but spare the media, to which Ampatuan Jr replied, "No ... Somebody can talk if we won't wipe out everybody."

The Ampatuans have denied the charges. Andal Ampatuan Jr and 16 policemen were the first to be charged and were led in handcuffs into the courtroom packed with anxious relatives and observers inside a Manila maximum-security prison.