U.S. prosecutors are preparing to unveil drug trafficking charges against the head of Venezuela's National Guard, according to people familiar with the case, as they investigate the suspected involvement of senior Venezuelan officials in the cocaine trade.

Nestor Reverol, the former head of Venezuela's anti-narcotics agency and a longtime ally of the late socialist President Hugo Chavez, is named in a sealed indictment pending in federal court in Brooklyn, New York, according to the people.

Reverol would be one of the highest-ranking Venezuelan officials to face U.S. drug charges. He could not be reached for comment by Reuters.