Democratic Republic of Congo on Wednesday accused Ugandan forces of shooting dead 12 Congolese fishermen last week on a lake straddling their shared border, something Uganda’s army denied.

One Ugandan soldier was killed when the countries’ navies clashed on Lake Edward.

Oil exploration near the lake has raised the stakes along the border, with each side periodically accusing the other of encroaching on its territory.

Obed Kambale, a spokesman for Congo’s fishing ministry, said Ugandan forces killed 12 fishermen last Friday following the previous day’s naval clashes. He said Ugandan troops arrested 92 fishermen last week.

“In the coming hours, a significant government delegation composed of the relevant ministries … will go to Kampala to begin talks with Ugandan authorities,” he said.

Uganda’s army spokesman Richard Karemire could not be immediately reached for comment but said over the weekend that reports of Ugandan troops killing Congolese fisherman were not true.

Uganda has a keen interest in eastern Congo’s lawless border zones and battled Congolese forces during a 1998-2003 war in the region in which millions of people died.

U.N. investigators have since accused it of backing rebel forces in eastern Congo — something it denies. The two countries have more recently coordinated operations against a Ugandan Islamist group active on Congolese soil.