* Ugandan troops hunting LRA rebels clash with Seleka gunmen
* Fighting took place near border with DR Congo
BANGUI, June 30 (Reuters) - Ugandan troops in Central African Republic (CAR) have killed at least 15 fighters from the mainly Muslim Seleka force, a group that has carved out fiefdoms in the country since leaving power earlier this year, local sources said on Monday.
Ugandan troops, backed by U.S. Special Forces, have been in CAR hunting down Ugandan Lords Resistance Army rebels, who have made the lawless nation one of their rear bases during a decade of preying on populations across the central African region.
However, the Ugandan troops clashed with fighters from the former Seleka rebel group in the remote east on Sunday and Monday, highlighting how the zone is awash with different armed groups. It was not immediately clear if U.S. troops were supporting Ugandan soldiers involved in the fighting.
"The Ugandans fired on our men by mistake after confusing them with the LRA," Eric Massi, a senior Seleka official in Bangui, told Reuters.
"There were 15 dead and three injured on our side. There were three dead and three injured on the Ugandan side," he added. "We are trying to calm things down."
Bienfait Walibanga, a priest in the Saint Joseph parish in Zako, in CAR's remote east close to the border with Democratic Republic of Congo, confirmed clashes between the two sides there and at the nearby village of Kono on Sunday and Monday.
He said a Ugandan soldier had been killed in an attack by Seleka fighters on Sunday, provoking a retaliation that killed two Seleka fighters.
Ugandan troops then killed 14 more Seleka fighters in further clashes on Monday, he said.
Seleka, a coalition of mainly Muslim rebels from northern CAR, seized power last year, but its time in Bangui, the capital, was marked by rights abuses, prompting mainly Christian self-defence militia to spring up across the country.
Nearly a million people - around a quarter of the population - have been forced from their homes in cycles of violence.
Seleka leaders stepped aside earlier this year under intense international pressure, but tit-for-tat killings continue and the former rebels still occupy pockets of the country, mainly to the north of Bangui.
About 100 U.S. Special Forces troops are supporting a 5,000-strong African Union regional force seeking to track down LRA leader Joseph Kony and his men, who are scattered across the thickly forested region straddling Central African Republic, South Sudan and Democratic Republic of Congo.
(Reporting by Crispin Dembassa-Kette; Writing by David Lewis and Steve Orlofsky)