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

Nestor Reverol, the former head of Venezuela's anti-narcotics agency, is named in a sealed indictment pending in federal court in New York, according to the people.

He would be one of the highest-ranking Venezuelan officials - and the only one currently in office - to face US drug charges.

Reverol, who leads the branch of Venezuela's armed forces that controls the country's borders, could not be reached for comment by Reuters.

In recent years, he has rejected US accusations that Venezuela has failed to curb illicit drug shipments and has touted the government's success in cracking down on the flow of cocaine from neighboring Colombia.

The National Guard did not respond to an e-mail seeking comment, and a National Guard press official contacted by telephone declined to comment. Venezuela's Information Ministry did not respond to an e-mailed request for reaction.

It is unclear what the specific charges are against Reverol, or when the charges against him will be made public.

US prosecutors have unsealed indictments charging at least five former Venezuelan officials with drug trafficking crimes over the past four years, according to records from district courts in Florida and New York.

Venezuelan President Nicolas Maduro dismisses charges of official involvement in drug trafficking as an international right-wing campaign to discredit Venezuela's government.