A senior Iranian official has defended shipping fuel to Venezuela, saying two independent countries are free to conduct trade and it is no one’s business.

Reports emerged May 14 that at least one Iranian tanker was loaded with fuel and sailing towards Venezuela. Both countries are under U.S. sanctions and Washington has said it is monitoring the situation.

Ali Rabiei who is President Hassan Rouhani’s chief of staff told a gathering of government executives on Saturday that Iran has trade relations with many countries including Venezuela, and this is not anyone else's concern, the official news agency IRNA reported.

In April, Iran's Mahan airlines conducted many flights to Venezuela in what was said to be shipping equipment and material to revive the country's refineries that are in disrepair to the long political turmoil gripping the government of Nicholas Maduro.

Later, U.S. envoy Elliot Abrams told a Spanish-language publication that Venezuela has shipped $500 million of gold to Iran in compensation for the assistance it receives.

"Our assumption is that those planes that come from Iran are bringing things for the oil industry, and they return full of gold as a form of payment," El Politico quoted Abrams as saying.

Now with the shipment of fuel, thought to be gasoline, the possibility emerges that Iran is actually selling refined oil products to the Maduro government, which is hard pressed by lack of transportation fuel.

Rabiei referring to "rumor mongering" said Iran and Venezuela exchange goods as two independent countries. He added that the two countries do not sit idle amid U.S. sanctions and try to sell their oil.