US says all UN sanctions on Iran restored

The United States faces defeat in its move to reimpose UN sanctions on Tehran, Iranian President Hassan Rouhani has said, as Washington declared all UN sanctions on Iran had been restored.

"America is approaching a certain defeat in its sanctions move ... It faced defeat and negative response from the international community," Rouhani said on Sunday in a televised speech.

"We will never yield to US pressure and Iran will give a crushing response to America's bullying," he said.

The Iranian rial fell to a record low against the US dollar on Sunday following the Trump administration's declaration.

The US currency was offered for as much as 273,000 rials, up from 267,800 rials on Saturday, according to foreign exchange site Bonbast.com, which tracks the unofficial market.

Iran has dismissed the US sanctions move as "void and illegal" and UN Secretary-General Antonio Guterres told the Security Council on Saturday he cannot take any action on the US declaration because "there would appear to be uncertainty" on the issue.

The three European parties to the nuclear deal - France, Britain and Germany - said in a statement on Sunday that any decision or action taken to reimpose UN sanctions "would be incapable of legal effect" because Washington used a mechanism agreed under a 2015 nuclear deal between Iran and world powers, which the United States quit in 2018.

However, Trump plans to issue an executive order allowing him to impose US sanctions on anyone violating sanctions against Iran.

Washington has unilaterally reimposed sanctions on Iran since 2018, which combined with a drop in oil prices have crippled the economy in Iran, which also has the highest COVID-19 death toll in the Middle East with 24,301 deaths.

Iran's rial has lost about 75 per cent of its value since 2018.