KHMER ROUGE ANNOUNCE OFFENSIVE

Khmer Rouge rebels said yesterday their forces were engaged in heavy fighting in Cambodia's second-largest city and had ambushed government tanks sent to relieve the beleaguered town. Western diplomats said the attack would be a blow to morale in Phnom Penh, which has lost control of large rural areas in the west to rebels but has so far held onto towns. The offensive could not be independently confirmed.

Defenders in the provincial capital of Battambang, 127 miles northwest of Phnom Penh, called in tanks to support them after the attack was launched Friday, Khmer Rouge radio said.

Diplomats said they had expected a rebel attack on a major town to mark the anniversary of the establishment of the Hun Sen government, which took over in Phnom Penh after Vietnam invaded the country in 1978 and ousted the Khmer Rouge.