Philippine politician 'to be charged' over massacre
Andal Ampatuan Jr (right) has been taken to Manila for questioning
A member of a powerful clan suspected of involvement in the killing in the Philippines of 57 people faces multiple murder charges, prosecutors say.
Andal Ampatuan Jr, a local mayor, surrendered to the authorities but denied organising the killings.
Troops and police swooped on towns run by the Ampatuan clan, arresting 20 men suspected of links with the killings.
The massacre happened on Monday, when a convoy of vehicles used by a rival politician was ambushed.
The passengers were taken to a remote hill region, shot at close range and their bodies dumped in shallow graves.
Mr Ampatuan Jr - mayor of Datu Unsay town - was taken by helicopter from his hometown in the restive Maguindanao province on Thursday morning to the nearby airport at General Santos City. From there he was flown to the capital Manila for questioning.
"It's not true," Mr Ampatuan Jr said when asked by reporters at General Santos City airport whether he had been involved in the massacre.
Chief State Prosecutor Jovencito Zuno said he would file murder charges against Mr Ampatuan Jr on Friday, Associated Press news agency reported.
The military said the Ampatuan family had voluntarily handed over Mr Ampatuan Jr to officials, including Jesus Dureza, an adviser to the president.
About 20 other suspects, including senior members of the Maguindanao's provincial police force and officers of Ampatuan township's force, are in custody and being investigated.
Police also rounded up and disarmed a 350-member militia force under the control of the Ampatuan clan, on Thursday.
Other members of the militia allegedly involved in the killings had fled and are being hunted in the hills of Maguindanao province.
The Philippines authorities have been coming under increasing pressure to bring the perpetrators of Monday's attack to justice, according to the BBC's South East Asia correspondent Rachel Harvey.
The Ampatuan clan have been loyal supporters of the president - but since the killings, Mr Ampatuan Jr, his father and his brother Zalday have been expelled from her party.
President Arroyo, who earlier declared a national day of mourning, has promised that the gunmen would not escape justice.
Philippine politician Ismael Mangudadatu has claimed it was gunmen loyal to the Ampatuans who ambushed his supporters as they were travelling to register his name for the polls.
Among the dead were Mr Mangudadatu's wife, his two sisters and several key supporters, as well as at least 18 journalists who were travelling with them to witness his registration as an election candidate.
Bodies buried after Philippines massacre
Between 10 and 15 motorists who witnessed the ambush were also among the victims, news agencies said.
The Ampatuans have effectively been in charge of Maguindanao for decades, analysts say.
Andal Ampatuan Sr has served in the Philippines Congress and won the governorship of Maguindanao unopposed for several terms.
His son was reportedly planning a similarly unopposed run to replace his father when Mr Mangudadatu decided to contest the office.
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