A Congolese rebel leader said that government aircraft bombed two rebel-held towns in northern Congo today, killing more than 500 people, just a few days after the guerrillas signed a peace deal.

Jean-Pierre Bemba, head of the Congolese Liberation Movement, said the government aircraft had dropped 18 bombs on Makanza and Bogbonga, about 420 miles northeast of Congo's capital, Kinshasa, killing 384 civilians and 134 rebel soldiers.

Congo's information minister, Didier Mumengi, said he did not know about any bombing, and Bemba's report could not be independently confirmed. If his account is accurate, however, the bombing would be one of the deadliest known attacks in Congo's year-long civil war.

On Sunday, Bemba signed a peace agreement that had already been adopted on July 10 by Congolese President Laurent Kabila and the leaders of five nations involved in the Congolese conflict. Bemba was the first rebel leader to sign the accord, and he said that he would only abide by it if another Congolese rebel group--the fractious Congolese Rally for Democracy--signed within seven days.

But speaking to reporters here in the Rwandan capital by satellite telephone, Bemba said today's bombing was a breach of the agreement by the government. "We're shocked. I consider Kabila has broken the cease-fire," Bemba said.

Bemba said both towns on the Congo River were packed with fishermen and rebel soldiers when two aircraft dropped bombs this morning.

Most of the population of the two towns, which face each other across the river, fled into surrounding forests fearing another attack, he said.

Strikes by government aircraft are usually made in Soviet-era Antonov transport planes equipped to carry bombs. They fly at high altitudes to escape antiaircraft fire and are often imprecise in hitting targets.