WASHINGTON, May 12 (Reuters) - A U.S. Marine Corps helicopter involved in disaster relief efforts in Nepal was declared missing on Tuesday while working in the vicinity of Charikot village, a spokesman for U.S. Pacific Command said.

Army Major David Eastburn, the spokesman, said U.S. military personnel were responding to the disappearance of the UH-1 Huey helicopter and the incident was under investigation. Eastburn said it was not immediately clear how many people may have been aboard the helicopter when it was declared missing.

Charikot was one of the villages hardest hit by a 7.3 magnitude quake on Tuesday. The quake was the worst aftershock following the 7.8 magnitude earthquake that hit Nepal last month.

(Reporting by David Alexander; Editing by Will Dunham)