By Mike Pflanz in Kibati and David Blair
The violence in the Democratic Republic of Congo entered a new phase when witnesses said that Angola had deployed troops against a rebel advance in the East.
Any arrival of foreign forces would mark a dangerous escalation. Under a peace accord which notionally ended the civil war in 2003, all outside armies withdrew from Congo. The return of foreign soldiers would reverse that agreement's main achievement.
Last month, President Joseph Kabila of Congo requested help from Angola to fight rebels led by Laurent Nkunda, the renegade Tutsi general, in the lawless eastern province of North Kivu.
The evidence suggests that Angola, which has one of Africa's most powerful armies, may have agreed. A senior Uruguayan officer with the United Nations peacekeeping force in Goma, the capital of North Kivu, told The Daily Telegraph that Angolan soldiers had been deployed in combat against the rebels.
"They have been camped above our position and we have heard them talking Portuguese. We understand it because we speak Spanish, for sure they are Angolan," he said.
If the UN commander's claim is proven, Rwanda may see the deployment as a provocation. President Paul Kagame could then respond by sending the Rwandan army back into Congo.
This would risk returning the giant country to the disastrous situation that prevailed between 1998 and 2003, when six African armies fought on its soil and plundered its mineral wealth.
Congo's last president was Mr Kabila's father, Laurent. To save his regime from Tutsi rebels supported by Rwanda,
Laurent Kabila received Angolan military help in 1998. Ten years later, his son may be repeating history.
An eight-day ceasefire collapsed when Gen Nkunda's rebels attacked a position held by Congo's chaotic national army in low hills near Kibati, eight miles north of Goma.
These clashes were the most serious since Oct 29, when the rebels advanced close to Goma itself before pulling back. Shooting continued throughout the afternoon, forcing people who had fled earlier rounds of fighting to move once again.
A long line of people filed into Goma as machine-gun fire and mortar explosions echoed around the hills. "There is nothing we can do but flee," said Angelique Ombeni, 32, as she walked with a bundle of clothes on her head. Her four children trotted to keep up with her, carrying plastic water cans and cooking pots. "We go somewhere and then we have to move again and again. Nowhere is safe for us in this fighting."
African leaders gathered for a regional summit in Kenya's capital, Nairobi, and demanded an immediate ceasefire.
"The Great Lakes region will not stand by and witness incessant and destructive acts of violence," read the summit's official communiqué.
Ban Ki-Moon, the UN secretary-general, also attended the summit and gave warning that Congo's "crisis could engulf the broader sub-region". He added: "We must put the cycle of violence behind us."
The UN has 17,000 peacekeeping troops in Congo - the largest such mission in the world. Mr Ban wants the Security Council to send another 3,000 soldiers. But the UN forces have not prevented Gen Nkunda's advance, nor have they intervened to protect civilians.
Mr Kabila's dilemma is that Congo's national army and the UN are both incapable of dealing with the rebel leader's challenge. Hence he has little choice but to ask for foreign military support. He may also choose to arm the brutal Mai Mai militia, his local allies in North Kivu.
But these moves would risk provoking his chief rival, Rwanda, and causing a spiral of bloodshed.