Four Ugandan soldiers and three civilians were killed Thursday in clashes on Lake Edward that lies between the two countries, a senior official in the Democratic Republic of Congo said.
Other clashes in the region between DR Congo forces and Ugandan rebels as well as a local militia claimed eight more lives, the army said.
A DR Congo naval patrol was "attacked this morning by a Ugandan patrol boat in Congolese waters," Donat Kibwana, the administrator of the Beni region in the eastern province of Nord-Kivu said.
"The Ugandan boat sank and four troops and three Ugandan civilians are dead," he said. "On the Congolese side, a soldier and a civilian have been injured."
The clash took place near the Congolese village of Kyavinyonge on Lake Edward.
Ugandan is yet to confirm the clashes and give its account of what happened.
There have been clashes between troops from both countries in recent times.
This week 18 Congolese fishermen were arrested by a Ugandan patrol boat while fishing in the Lake.
The Congolese soldiers have consistently fought persons they deem to be rebels or militia fighters entering the country from Uganda and Rwanda.