The first of five tankers carrying much-needed Iranian fuel and oil products entered Venezuelan waters on Saturday, a Venezuelan government official said.

"The ships of the sister Islamic Republic of Iran are in our exclusive economic zone," Venezuelan oil minister Tareck El Aissami wrote on Twitter after the arrival of the first tanker, named Fortune.

The fleet is carrying about 1.5 million barrels of gasoline according to media reports, and arrives amid tensions between Tehran and Washington, which has imposed sanctions on Venezuelan oil exports and Iran.

Venezuela had said its navy and air force would escort the tankers after Tehran warned of "consequences" if the US stopped the ships from reaching their destination.

The United States calls Maduro a "dictator", however, and has levelled a battery of economic sanctions against his administration, including an oil embargo that came into force in April 2019.