The Foreign Ministry sent a formal protest to the United Nations on Friday alleging U.S. violations of Panama's sovereignty during a firefight involving U.S. Marines this week.

The protest said U.S. troops closed a Panamanian highway just outside the capital for three hours Tuesday night after fighting broke out between "soldiers of the United States and an unknown group."At a news conference called by the U.S. military, Marine 1st Sgt. Alexander J. Nevglovski Sr. said Friday that his company became engaged in a gunfight Tuesday night at a fuel depot with uniformed men "who were using us as training aids."

"They were highly professional," Nevglovski, who has served for 24 years in the Marine Corps, told the news conference at the U.S. Southern Command's headquarters. "They were good. They were trying to provoke us."

Nevglovski, of Camp Lejeune, N.C., said the intruders wore black uniforms and carried sophisticated night-vision equipment, but he declined to speculate on whether they were members of the Panamanian Defense Forces.