U.N. troops and ex-soldiers from Haiti's (search) disbanded army fought two gun battles in the country's west and center on Sunday, killing at least four people, including two peacekeepers, in the deadliest day for the 10-month-old U.N. mission, officials said.

The Sri Lankan and Nepalese soldiers who died were the first peacekeepers killed in clashes since the U.N. force arrived in June 2004 to try and stabilize the impoverished, volatile nation, officials said.

The Sri Lankan was killed in a raid on a police station occupied by armed ex-soldiers in Petit-Goave, an ex-soldier stronghold about 45 miles (72 kilometers) west of Port-au-Prince (search), U.N. spokesman Toussaint Kongo-Doudou said.

"We lost one man," Kongo-Doudou said, adding that three other peacekeepers were injured and in stable condition. Two ex-soldiers died and 10 others were wounded.

The U.N. troops entered Petit-Goave (search) in a pre-dawn operation to remove ex-soldiers from the police station. Using a loudspeaker, the Brazilian commander of U.N. troops in Haiti, Lt. Gen. Augusto Heleno Ribeiro, tried for 20 minutes to get the former soldiers to surrender peacefully when they opened fire on U.N. troops, Kongo-Doudou said.

Later Sunday, a group of Nepalese soldiers driving to the central town of Hinche exchanged gunfire with a different group of former soldiers, U.N. spokesman Damian Onses-Cardona said. The ex-soldiers killed one Nepalese and stole one of their vehicles. It wasn't clear if the ex-soldiers suffered any casualties.