Washington: The US Treasury imposed sanctions on Thursday against six individuals and three companies it said had funnelled millions of dollars to the Iranian Revolutionary Guard’s elite Quds Force, just days after President Donald Trump withdrew from the landmark 2015 Iran nuclear deal.

The Treasury Department accused Iran’s central bank of actively helping the group access US dollars held in foreign banks.

“The Iranian regime and its Central Bank have abused access to entities... to acquire US dollars to fund the IRGC-QF’s malign activities, including to fund and arm its regional proxy groups, by concealing the purpose for which the US dollars were acquired,” Mnuchin said in a statement.

The six individuals and three entities were sanctioned under US regulations targeting specially designated global terrorist suspects and Iranian financial activity, the Treasury said.

The crackdown comes two days after Trump withdrew from the 2015 arms accord and as US Secretary of State Mike Pompeo pushes allies in Europe, Asia and the Middle East to pressure Iran to return to negotiations over its nuclear and missile programmes.

Trump’s decision has given grace periods of 90 days to six months for companies to wind down their trade with Iran.

In February 2015, Reuters reported that at least $1 billion in cash had been smuggled into Iran despite US and other sanctions. Before it reached Iran, the cash was passed through money changers and front companies, sources told Reuters.

The report said Iran’s central bank had worked with other entities, including sanctioned Iranian companies, to find ways to obtain US dollars, including using front companies and their networks. They said the central bank had given the orders to the front companies abroad to buy dollars.