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.

According to shipping tracker MarineTraffic, as of at 9:00 pm local time (0100 GMT Sunday) Fortune was near the coast of Sucre state in northern Venezuela after passing off Trinidad and Tobago.

It plans to sail to the El Palito refinery in Puerto Cabello in northern Carabobo state, according to the state-run television station.

The rest of the Iranian ships -- the Forest, Petunia, Faxon and Clavel -- will arrive in the next few days, according to state television.

Relations between Caracas and Tehran have become close since former Venezuelan president Hugo Chavez took power in 1999.

Iran has repeatedly expressed its support for Nicolas Maduro, his successor, who is also supported by Russia, China, Turkey and Cuba.

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

The fuel from Iran comes at a time when the shortage of gasoline, chronic for years in some parts of the country, has worsened in the midst of the COVID-19 pandemic.

Venezuela has the largest oil reserves in the world, but its production is in freefall, a collapse that experts attribute to failed policies, lack of investment and corruption.