The fierce confrontation between Rwandan and Ugandan troops in Kisangani has caused serious strains in a long-standing African alliance, while also casting doubts on the viability of the whole Congolese peace process.

The scale of the fighting which broke out over the weekend of August 15-16 shocked the leaderships of both countries, forcing a quick summit in Uganda.

But the tensions between the rival armies go back a long way, with Uganda and Rwanda increasingly at odds over the conduct of the war in the Democratic Republic of Congo and how best to end it.

Having been instrumental in securing Laurent Kabila's victory against the late President Mobutu Sese Seko in May 1997, Uganda and Rwanda both turned against their former protégé.

They accused President Kabila of reneging on policy commitments, of allowing Ugandan and Rwandan insurgents to operate on Congolese territory and forging a close relationship with a Sudanese government openly hostile to Uganda.

No common agenda

Key player: Rwandan vice-president Paul Kagame

When a rebellion broke out against President Kabila in August 1998, there were immediate suspicions that Uganda and Rwanda were behind the call to arms.

Despite the emergence of the Congolese Rally for Democracy (RCD), a broad-based coalition with its own constitution, political structures and manifesto, it was clear that commanders from the Rwandan Patriotic Army (RPA) and the Ugandan People's Defence Forces (UPDF) were directing the rebel army - just as they had supervised President Kabila's troops in the previous war.

But beyond a strong antipathy towards Laurent Kabila and his allies, there has been little evidence of a common war agenda for the governments in Kampala and Kigali.

Rwandan officials were quick to voice misgivings about Ugandan military operations in the north-east of the DR Congo, arguing that senior Ugandan figures were manipulating the war for their own ends such as working mining concessions in rebel territory.

Top-level talks produced a rough code of practice for the belligerents, but the Rwandan government says the Ugandans have never taken it seriously.

Timber and diamonds

There were also sharp disagreements between rival commanders in Kisangani, DR Congo's third city.

South African foreign minister Dr Nkosazana Zuma is trying to broker peace among rebels

War aims became blurred as attention focused instead on the large contingents of UPDF and RPA troops, both policing different areas, and both weakening the RCD's credibility as a political and military movement.

Although far from prosperous itself, Kisangani is a major trading centre for timber and diamonds, its airport playing a vital role in the rebel economy.

Rwanda clearly resented Uganda's growing hold on the city and the whole north-east region, but polite reservations turned into a clear policy rift with the emergence of Jean-Pierre Bemba and his rival Congolese Liberation Movement (MLC) in November 1998.

Jean Pierre-Bemba challenged dominance of RDC

Exploiting the RCD's lack of charisma and inability to win popular support, Bemba announced a series of victories in the far north.

A self-styled businessman-turned-warrior, he was dismissed by Rwanda and the RCD as a dangerous maverick, but was clearly taken seriously by the Ugandan military.

Lack of coordination

Despite Bemba's denials of outside support, there have been strong suggestions that the UPDF has run his campaign and done most of his fighting.

For Rwanda and the RCD, Bemba's northern front was little more than a sideshow, with the real war being fought further south in Kasai and Katanga.

There was clearly a lack of coordination between the military planners in Kampala and Kigali.

On the diplomatic front, divisions also opened up.

Ugandan President Yoweri Museveni accepted Colonel Muammar Gadhafi's invitation to sign a ceasefire, along with Laurent Kabila, at Sirte in April.

Rwanda did not attend and ministers in Kigali hinted there had been no prior warning from the Ugandans.

Tensions rising

But it was the change in the leadership of the RCD in May which brought a simmering antagonism into the open.

Rwanda backed the rebels' decision to remove RCD President Ernest Wamba-dia-Wamba, Uganda did not.

While Emile Ilunga took over the RCD operation in Goma, Wamba re-established his headquarters in Kisangani and won the support and protection of the UPDF.

Sticking to his guns: Wamba dia Wamba

Denounced by the Rwandans as a spent force who should retire discreetly, Wamba was saluted in Kampala as the only legitimate leader of the rebellion - victim of a cynical coup.

The past three months have seen tensions steadily rise in Kisangani, with the peace agreement brokered by Zambia in July doing nothing to heal divisions.

The two competing wings of the RCD are now at war over who should sign a peace agreement, already endorsed by Rwanda, Uganda and the DR Congo, with the Zambian government trying to verify which has the better credentials.