Emergency rule has been imposed on two Philippine provinces after security forces found more bodies from one of the worst incidents of election violence in the nation's history.

The death roll rose to 46 when police and soldiers found another 22 bodies in a hillside mass grave.

This added to the 24 bodies previously found near the scene of Monday's massacre in Maguindanao province.

The area is racked by violent political rivalries, in addition to a long-running Islamic insurgency, but the killings have shocked the nation. One adviser to President Gloria Macapagal Arroyo described the massacre as the worst in the country's recent history.

Dozens of gunmen abducted the group of journalists, supporters and relatives of a candidate for governor as they travelled through Amputuan township to lodge candidacy documents in the provincial capital for May 2010 elections.

The candidate, Ismael Mangudadatu, who was not a part of the convoy, accused a powerful political rival from the Amputuan clan of being behind the killings. There is a long-standing bitterness between the two families.

Mr Mangudadatu's wife, Genalyn, and his two sisters, were among the dead.

The bodies found in the grave, about six feet deep, were dumped on top of one another. They included a pregnant woman. Grieving relatives helped identify their loved ones before they were given the bodies, covered by banana leaves, for burial.

Officials were still trying to determine the exact number of people intercepted by the gunmen and whether any had survived.

Ms Arroyo declared an emergency in the provinces of Maguindanao and nearby Sultan Kudarat, allowing security forces to conduct random searches and set up checkpoints to pursue the gunmen.