US Secretary of State Condoleezza Rice met with leaders from troubled African nations Wednesday, calling for greater vigilance in keeping out "negative forces" from Congo and a robust peacekeeping force for war-torn Somalia.

Rice's 24-hour visit to the vast Horn of Africa nation was meant to spur movement on long-festering conflicts and comes ahead of a Europe-Africa summit in Lisbon this week which is set to focus on trade deals and development as well as bolstering security on the continent.

Rice met with the leaders of Uganda, Rwanda and Burundi and a senior official from Congo, who all committed to better monitor their shared borders to prevent rebels from slipping across.

"They commit again not to harbour negative forces, the illegal groups, militia and armed groups causing destabilization," Rice said after the meeting, adding without going into detail that a "third party" should be tasked with supporting the Great Lakes countries.

Eastern Congo is engulfed in fighting between the army and forces loyal to a dissident general who demands the disarmament of a rebel group linked to the perpetrators of Rwanda's 1994 genocide.

Rice also met with Somalia's new Prime Minister Nur Hassan Hussein and stressed the need for more African troops to secure peace in the volatile capital Mogadishu.

Hussein's government was plunged into turmoil this week when five ministers resigned. Forces loyal to his government are battling alongside Ethiopian troops a persistent insurgency that has sparked a humanitarian catastrophe.

"We do believe that Ethiopian forces should not have to stay in Somalia past a certain point but will require fairly robust peacekeeping forces," Rice said.

She was also expected to push Sudanese officials on the delayed deployment of a hybrid United Nations-African Union peacekeeping force of 26,000 for embattled Darfur, a conflict which has seen more than 200,000 people killed.

A tottering peace deal between Khartoum's Islamist government and former southern rebels was also set to be on the agenda.

Earlier, upon arrival, Rice told journalists she was "increasingly concerned about several crisis spots in Africa," including Somalia, Sudan and Congo - none of whose presidents attended the meet.

Ethiopia is Washington's strongest ally in a region mired in chaos and conflict. It led a US-blessed assault on a popular Islamist group in Somalia at the New Year, which has been followed by endless, brutal violence from which it has been unable to extract itself.

But Ethiopia is cracking down on an insurgency of its own in the remote east, and has been charged with egregious human rights violations, which the US has been accused of turning a blind eye to.

The two nations were also set to discuss deteriorating relations with Ethiopia's arch-foe Eritrea, which fought a bloody 1998-2000 border war with Ethiopia that killed 70,000 people. Relations between the neighbours are still fraught.

This was Rice's second visit to sub-Saharan Africa in two years.