KIGALI, Rwanda (AP) _ Congolese rebels warned the government Wednesday to halt a massive bombardment, threatening to take revenge against 700 Zimbabwean troops the insurgents have surrounded.

Rebel spokesman Kin-Kiey Mulumba said government forces were using planes, helicopters, river gunboats and heavy artillery to break through rebel lines at Bokungu, 480 miles northeast of capital, Kinshasa, and link up with besieged Zimbabwean troops at Ikela airport.

``The fighting is extremely violent,'' Mulumba said. ``We're continuing to resist. But if they continue, the Zimbabweans at Ikela will find themselves in a bloodbath.''

Mulumba said the fighting was the fiercest since the signing of a peace accord in August that was supposed to establish a cease-fire and pave the way for the deployment of U.N. peacekeepers and the withdrawal of foreign forces.

The agreement was signed between Congo's President Laurent Kabila and his allies from Zimbabwe, Angola and Namibia, and the rebels and their allies, Rwanda and Uganda.

Since the signing, the rebels and the government have regularly accused each other of cease-fire violations and a lack of trust to implement the agreement.

Attempts to secure a safe passage for the Zimbabwean forces trapped in Ikela, 185 miles east of Bokungu, have failed because they have refused rebel conditions to surrender their weapons, vehicles and ammunition.

On Tuesday, Kabila bombed Bokungu twice with two Soviet-era Antonov-26 transport aircraft, Mulumba said.

Another rebel security source, speaking on condition of anonymity, said the town had fallen to the government hands before it was recaptured by the rebels on Tuesday.

Mulumba denied Zimbabwean accusations that American mercenaries were manning artillery and communications equipment for the rebels in southern Congo.

``I'm categorically denying that we have any mercenaries on our side. Least of all Americans,'' Mulumba said.