An assault by anti-government Marxist guerrillas on the mountain hideout of a right-wing militia leader has led to clashes between the guerrillas and nearby army troops in which at least 60 combatants have died, military authorities said today.

A military spokesman in northern Cordoba Province said at least 32 soldiers have been killed -- the highest army death toll in a single action since January, when the government began formal peace talks with leaders of the rebel Revolutionary Armed Forces of Colombia. Still, the fighting seemed unlikely to upset negotiations aimed at ending the 30-year-old conflict, and the next round of talks remains set for July 6.

Army and local officials said the troops came under fire Tuesday night as they hunted for a group of 500 rebels who had been trying to push into the Nudo de Paramillo mountain range -- stronghold of the rebels' most bitter enemy, Carlos Castano. Castano heads an illegal, nationwide alliance of right-wing paramilitary squads known as the United Self-Defense Forces of Colombia.

The continuing battle follows a series of high-profile attacks by a smaller guerrilla group, the National Liberation Army, which hijacked an airliner in early April and kidnapped all 41 people aboard. Last month, the group kidnapped more than 150 people at a church in the city of Cali, calling the action retaliation for killings by right-wing militiamen. The guerrillas still hold 54 captives from the two incidents.