Washington on Tuesday slapped sanctions on a China-based company. The United States accused the firm of acting on behalf of US-blacklisted Mahan Air, the Treasury Department said, denouncing the Iranian airline’s flights to Venezuela.

The Treasury said in a statement that Shanghai Saint Logistics Limited acted as a general sales agent for Mahan Air. Washington blacklisted the airline in 2011 over the report it reportedly provided to Iran’s Islamic Revolutionary Guard Corps.

Tuesday’s action freezes any US-held assets of Shanghai Saint Logistics and generally bars US citizens from doing business with the company.

“This designation serves as another reminder that companies still providing services for Mahan Air – in the PRC or anywhere else – risk potential US sanctions,” US Secretary of State Mike Pompeo said in a statement, using the acronym for the People’s Republic of China.

The Treasury said Mahan Air is operating charter flights to Venezuela for Iranian technicians and technical equipment, using materials sourced from China, in support of Venezuelan President Nicolas Maduro and paid for by the government with gold bars from the Central Bank of Venezuela.

“The Iranian regime is using Mahan Air to support an illegitimate and corrupt regime in Venezuela,” Treasury Secretary Steven Mnuchin said.

The US and dozens of other nations recognised Venezuelan opposition leader Juan Guaido as interim president last year. But Maduro remains in power, backed by Venezuela’s military, as well as Russia, China, Cuba and Iran.

The US also maintains punishing sanctions on Iran, measures that were reimposed after US President Donald Trump pulled out of an international nuclear deal with Tehran, as well additional sanctions aimed at containing its regional power in the Middle East.

A senior US official told Reuters last week that the administration is considering measures it could take in response to Iran’s shipment of fuel to crisis-stricken Venezuela.