Rwandan commanders say Ugandan troops stationed at the city's main airport opened fire on Rwandan positions a short distance away.

The Rwandan troops returned fire, and are said to have wounded several Ugandan soldiers.

The Rwandans accused Uganda of provoking an incident in an attempt to secure control of the airport, 25 kilometers (15 miles) east of the city, where supplies are flown in daily.

"The Ugandan army deployed troops all night to surround the airport, and they tried to block us in, they fired and there was a skirmish," said Rwandan Government spokesman Lieutenant Colonel Wilson Rutayisire.

"The Ugandan army then rallied again, directly attacking our troops, but we pushed them back," he said.

One Rwandan soldier was slightly wounded in the hour-long clash, Rwandan officers said.

Rival factions

Rwanda and Uganda support opposing rebel factions in Congo who have been waging a year long rebellion to oust President Laurent Kabila.

The two countries signed a peace agreement with the president last month. But they differ over how to end the war and have taken different sides in the leadership dispute in the main rebel movement, the Congolese Rally for Democracy (RCD).

Former rebel leader Ernest Wamba dia Wamba was ousted as head of the RCD in May, but refused to step down.

With Ugandan backing Mr Wamba established new headquarters in Kisangani, where Ugandan forces have been flying in troops to bolster him and his supporters.

The RCD's dominant faction, backed by Rwanda and headed by Mr Wamba's successor Emile Ilunga, is based in Goma, in eastern Congo.