Elliott Abrams, the US special envoy for Venezuela, said that Iran has been sending "more and more planes" to the South American nation, including this week.
"Our guess is that they are being paid in gold," he said at the Hudson Institute, a conservative Washington think tank.
"Those planes that are coming in from Iran that are bringing things for the oil industry are returning with the payments for those things: gold,” Agence France Presse quoted him as saying.
President Donald Trump's administration has slapped unilateral US sanctions aimed at ending oil exports from both Iran and Venezuela.
Venezuela's economy has been collapsing, with millions fleeing as they lack basic goods, and Iran has also taken a hit from US sanctions.
Abrams charged that Iran's role showed soft support for Venezuela's leftist leader Nicolas Maduro from Russia and China, which have stood by him despite Western pressure.
"One of the reasons I mention that is not just to show that Iran is playing an increasing role, but notice that it's cash," Abrams said.
"We know that Maduro has over the last year wanted Russian and Chinese additional loans, additional investments, and he has not gotten a dime," he said.
Secretary of State Mike Pompeo on Wednesday also highlighted the two US nemeses' cooperation, saying that "multiple" aircraft had been spotted in Venezuela from Iran's Mahan Air.
The carrier is under US and other sanctions for transporting fighters and weapons on behalf of Iran's Revolutionary Guards.
"These flights must stop and countries should do their part to deny overflights just as many have already denied landing rights to this sanctioned airline," Pompeo told reporters.
Copyright © Saudi Research and Publishing Co. All rights reserved.