Philippine officials have put a southern province under martial law and have arrested the patriarch of a powerful clan following last week's massacre of 57 people.

Government officials say President Gloria Arroyo suspended civil rights in Maguindanao province Saturday, allowing troops to make arrests without warrants.

They say troops took Andal Ampatuan Senior and his son Zaldy Ampatuam into custody at their home in Maguindanao.  Another of Ampatuan's sons, Andal Ampatuan Junior, is already in jail in connection with the massacre.

More than 100 soldiers and dozens of police raided homes belonging to the Ampatuan family Friday.

The Ampatuan clan has ruled the southern province of Maguindanao for more than a decade.

During the November 23 massacre, about 100 gunmen attacked and slaughtered members of a convoy traveling to register politician Esmael Mangudadatu for governor - challenging the Ampatuan clan's hold on power. 

The dead included Mangudadatu's wife, sisters, and supporters.  More than half the victims were journalists.

President Arroyo has faced intense pressure to take action against the violence because of her political ties to the Ampatuan clan.  She continues to promise justice will be served. 

Some information for this report was provided by AP, AFP and Reuters.