Iran’s president dismissed US efforts to restore all UN sanctions on the country, as mounting economic pressure from Washington pushed the currency down to its lowest level ever on Sunday.

Iran’s currency dropped to 272,500 to the US dollar at money exchange offices across Tehran.

The rial has lost more than 30% of its value to the dollar since June as sweeping US sanctions on Iran continue to crush its ability to sell oil globally.

Iran’s currency was at 32,000 rials to the dollar at the time of Tehran’s 2015 nuclear deal with world powers, which was signed by the Obama administration but which the Trump administration pulled the US out of.

As the currency plummeted, Iran’s president Hassan Rouhani attacked the Trump administration’s declaration on Saturday that all UN sanctions against Iran have been reimposed because Tehran is not complying with the nuclear deal.

“If America uses its bullying … and does something in practice, it will have to face our decisive response,” Mr Rouhani said in a cabinet meeting Sunday.

The US move to reimpose sanctions has been rejected as illegal by most of the rest of the world and sets the stage for an ugly showdown at the world body ahead of its annual General Assembly this week.

UN secretary-general Antonio Guterres said the UN will not support reimposing sanctions on Iran until he gets a green light from the Security Council.

He said in a letter to the council president, obtained on Sunday by The Associated Press, that “there would appear to be uncertainty” on whether or not US Secretary of State Mike Pompeo triggered the “snapback” mechanism in the Security Council resolution that enshrined the 2015 nuclear deal between Iran and six major powers.

Even before the US declaration, other Security Council members had vowed to ignore it.

They say the US lost legal standing to invoke snapback sanctions when President Donald Trump withdrew from the nuclear deal in 2018 and began reimposing US sanctions on Iran.

France, Germany and the UK issued a joint statement Sunday reiterating that they contest the legal basis of the Trump administration’s bid to activate the snapback sanctions mechanism because the United States withdrew from the nuclear accord.

The statement said “it follows that any decision or action taken on the basis of this procedure … are without effect in law”. They stressed they remain determined to preserve the nuclear deal with Iran.

Israeli foreign minister Gabi Ashkenazi on Sunday welcomed the US sanctions efforts.

He called on France, Britain and Germany to withdraw their opposition and support a “rigorous implementation of the sanctions”.

Israel views Iran as its greatest threat, and has hailed Mr Trump’s decision to withdraw from the 2015 nuclear deal and reimpose sanctions.

Iran’s foreign ministry spokesman Saeed Khatibzadeh said the snapback sanctions have only happened in “the fantastical world” of the Trump administration. He said the US stands on the wrong side of history.

“They are attempting to make everyone believe it, but nobody is buying it except for themselves,” Mr Khatibzadeh said during his weekly press briefing on Sunday.

“It is a television show whose sole presenter, viewers and those cheering it on are Mr Pompeo himself and a handful of others,” the spokesman said.

The White House plans to issue an executive order on Monday spelling out how the US will enforce the restored sanctions, and the state and treasury departments are expected to outline how foreign individuals and businesses will be penalised for violations.

Tensions are running high between Iran and the US, particularly since a US strike in January killed Iranian Revolutionary Guard general Qassem Soleimani in Baghdad, prompting Tehran to retaliate with a ballistic missile strike on Iraqi bases housing American troops.