The brother of Andal Ampatuan is escorted by police officers in a round-up of the Ampatuan clan yesterday

Philippine troops took the patriarch of a powerful clan – a former governor – and three other members of his family into custody yesterday after the president put a southern province of the southeast Asian nation under martial law to hunt down suspects in the country's worst political violence.

The head of the clan, Andal Ampatuan Sr, and at least six other family members who have ruled impoverished Maguindanao province unopposed for years, are the main suspects in the 23 November attack on a political rival's convoy in which 57 people, including 30 journalists, were killed. The family denied involvement.

President Gloria Macapagal has allowed troops to make arrests without court warrants and restore order in the province.