GOMA, Democratic Republic of Congo: Democratic Republic of Congo and Ugandan armed forces exchanged gunfire on a lake straddling their shared border, wounding at least two Congolese soldiers, a Congolese official said.

The two countries have a sometimes tense relationship, with the Congolese accusing Ugandan forces of encroaching on their territory and Ugandan authorities saying the Congolese do not do enough to stamp out militia activity near the border.

The clashes occurred on Thursday on Lake Edward, which divides northeastern Congo from northwestern Uganda, Donat Kibwana, the administrator of Congo’s Beni territory, told Reuters.

Congo’s navy had launched a patrol after several Congolese fishing boats were stopped on Wednesday by Ugandan forces, whom Kibwana accused of entering Congolese waters.

“This is how the patrol found itself ambushed by the Ugandan navy,” Kibwana said. “Clashes followed that resulted in two people wounded from the Congolese army, and the Ugandan vessel was hit by gunshots from the Congolese army.” He said he did not yet have information on any Ugandan casualties. Uganda’s army spokesman could not be immediately reached for comment.

Congo and Uganda were enemies during a 1998-2003 conflict in eastern Congo that resulted in millions of deaths. UN investigators also accused Uganda in 2012 of backing an insurrection in the area, charges it denied.

However, the countries have also said they are jointly planning military operations against a Ugandan rebel group that has been blamed for hundreds of civilian deaths in Beni since 2014.