The new US sanctions targeting Iran’s supreme leader and other top officials mean the “permanent closure” of diplomacy between Tehran and Washington, Iran’s Foreign Ministry spokesman has said.

That is according to a report carried by the state-run IRNA news agency on Tuesday, quoting spokesman Abbas Mousavi.

Mr Mousavi says the “fruitless sanction on Iran’s leadership and the chief of Iranian diplomacy mean the permanent closure of the road of diplomacy with the frustrated US administration”.

US president Donald Trump enacted new sanctions on Monday targeting Iran’s Supreme Leader Ayatollah Ali Khamenei.

US officials also say they are planning sanctions against Iranian Foreign Minister Mohammad Javad Zarif.

Washington says the measures were taken to discourage Tehran from developing nuclear weapons and supporting militant groups.

They came amid heightened tensions between Iran and the US over Tehran’s unravelling nuclear deal with world powers.

Mr Mousavi’s statement echoed that of Iran’s UN ambassador, Majid Takht Ravanchi, who warned on Monday that the situation in the Persian Gulf was “very dangerous” and that any talks with the US were impossible in the face of escalating sanctions and intimidation.

However, US national security adviser John Bolton said Mr Trump is open to real negotiations and “all that Iran needs to do is walk through that open door”.

Mr Bolton was speaking at a high-profile security summit in Jerusalem.

He said American envoys are surging across the region in hopes of finding a path out of escalating tensions between the US and Iran but that the silence of the Islamic Republic has been “deafening”.

Mr Bolton said: “There is simply no evidence that Iran has made the strategic decision to renounce nuclear weapons.”

Meanwhile, the US envoy at the United Nations, Jonathan Cohen, said the Trump administration’s aim was to get Tehran back to negotiations.

The sanctions follow Iran’s downing last week of a US surveillance drone, worth over 100 million US dollars (£78.4 million), over the Strait of Hormuz, an attack that sharply escalated the crisis in the Persian Gulf.

After the downing of the drone, Mr Trump pulled back from the brink of retaliatory military strikes but continued his pressure campaign against Iran.

Mr Trump last year re-imposed sanction on Iran after pulling the US out of the nuclear pact that world powers made with Tehran in 2015.

Other nations stayed in the deal, which eased sanctions on Iran in exchange for curbing its nuclear programme.

The latest round of sanctions denies Mr Khamenei and senior Iranian military figures access to financial resources and blocks their access to any financial assets they have under US jurisdiction.

US Secretary of State Mike Pompeo
US Secretary of State Mike Pompeo is currently in the Middle East (AP Photo/Jacquelyn Martin, Pool)

Mr Trump said the new sanctions were not only in response to the downing of the American drone.

The US has blamed Iran for attacks on two oil tankers this month near the Strait of Hormuz. Citing those episodes and intelligence about other Iranian threats, the US has sent an aircraft carrier to the Persian Gulf region and deployed additional troops alongside the tens of thousands already there.

The sanctions were announced as US Secretary of State Mike Pompeo was holding talks in the Middle East with officials in the United Arab Emirates and Saudi Arabia about building a broad, global coalition that includes Asian and European countries to counter Iran.

Mr Pompeo is likely to face a tough sell in Europe and Asia, particularly from those nations still committed to the 2015 nuclear deal.