The Philippines authorities have charged 197 people with murder in connection with the massacre of 57 people in the province of Maguindanao last November.

Those charged include former governor Andal Ampatuan Sr., head of the powerful Ampatuan clan. His son has already been accused of masterminding the killings.

Public prosecutors say Andal Ampatuan Jr. and his supporters carried out the killings to prevent a political rival from taking part in May's elections for the post of governor.

The Ampatuan clan, allies of Philippine President Gloria Arroyo, were long regarded as the ultimate authority in the province of Maguindanao.