And as earlier optimism over the talks deflated, one of the Congolese rebel factions represented in Lusaka said it had captured the key northern town of Gbadolite, sending 5,000 Congolese troops and allied Rwandan Hutu militiamen fleeing.

The BBC's Ishbel Mathieson: "These are serious negotiations"

Jean-Pierre Bemba, leader of the Uganda-backed Congolese Liberation Movement said five rebel battalions had surrounded and captured Gbadolite, 1,200km northeast of the capital, Kinshasa, and home town of Congo's fomer dictator, President Mobutu.

He said they also captured its strategic airport, used by the Congolese Government and its allies to bomb rebel positions.

While the report could not be confirmed independently, airport officials in Kinshasa said the army had canceled two scheduled flights to Gbadolite, raising suspicion over its control of the town.

Stalled talks

A draft agreement calling for a national dialogue among the Congolese groups, formation of a joint army and deployment of international peacekeepers to enforce a ceasefire has not yet been signed by regional foreign and defence ministers from all the countries involved in the fighting.

Rwanda and Uganda are insisting that Congo and its allies disarm and send back thousands of Rwandan Hutu militiamen responsible for the 1994 genocide in Rwanda, who are fighting alongside the Congolese Armed Forces.

The Congolese Government and the rebels appear to agree in principle on the withdrawal of foreign troops, but disagree over the composition of a peacekeeping force in Congo.

The parties are looking at the possibility that rebel forces in DR Congo could be absorbed into the official armed forces.

Mbeki confident

If the delegations do agree a formula acceptable to regional foreign and defence ministers, it will have to be ratified by a summit of regional heads of state.

South African President Thabo Mbeki said on Sunday he was convinced that a ceasefire agreement would soon be reached.

"Great progress has been achieved in the negotiations currently taking place in Lusaka, Zambia," he told international business and political leaders gathered in Durban for the ninth annual Southern African economic summit.

"We are convinced that, despite all the difficult issues that had to be resolved, agreement will be reached soon," Mr Mbeki added.

On Saturday, both rebel spokesmen and representatives of the Congolese Government expressed optimism that an accord would be reached.