Fighting has escalated in northwest Cambodia in the past week, sending thousands of refugees and wounded civilians into nearby towns, relief workers said Thursday.

More than 400 families have arrived in the provincial capital of Sisophon in the past few days, according to reports from relief workers there.Other familes have been forced to take refuge in nearby Battambang, the country' s second-largest city.

Foreign relief workers at Battambang reported heavy fighting between government and Khmer Rouge guerrilla forces at Phnom Sampon, west of the city, at Banan to the south, Bavel to the northwest and along Route 10 to the Khmer Rouge-held district of Pailin near the Thai border.