The US has imposed sanctions on Iran’s foreign minister Mohammad Javad Zarif - ratcheting up tensions between the two countries and denting the possibility of diplomatic talks.

Mr Zarif - a key figure in the now-abandoned Iran nuclear deal, and an outspoken critic of the US on Twitter - insisted the move would have no effect on him as he has no US property.

Imposing the sanctions, Treasury secretary Steven Mnuchin said: "Javad Zarif implements the reckless agenda of Iran’s Supreme Leader, and is the regime's primary spokesperson around the world.

"The United States is sending a clear message to the Iranian regime that its recent behaviour is completely unacceptable."

In a tweeted response, Mr Zarif was defiant: “The US' reason for designating me is that I am Iran's 'primary spokesperson around the world’. Is the truth really that painful? It has no effect on me or my family, as I have no property or interests outside of Iran. Thank you for considering me such a huge threat to your agenda."

In photos: British-flagged tanker seized by Iran Show all 13 1 /13 In photos: British-flagged tanker seized by Iran In photos: British-flagged tanker seized by Iran A speedboat of Iran's Revolutionary Guard moving around the British-flagged oil tanker Stena Impero Tasnim News Agency/AP In photos: British-flagged tanker seized by Iran Crew members of the British-flagged tanker Stena Impero, that was seized by Iran in the Strait of Hormuz EPA/IRIB News Agency In photos: British-flagged tanker seized by Iran A satellite image of the Iranian port city of Bandar Abbas reveals the presence of the seized British oil tanker, the Stena Impero on July 22 Maxar Technologies/Reuters In photos: British-flagged tanker seized by Iran Iranian Revolutionary Guard Corps (IRGC) claims to have seized Stena Impero at the Strait of Hormuz with 23 crew on board on 20 July EPA/IRIB News Agency In photos: British-flagged tanker seized by Iran Iranian Revolutionary Guards patrolling around the captured British-flagged tanker Stena Impero as it's anchored off the Iranian port city of Bandar Abbas AFP/Getty In photos: British-flagged tanker seized by Iran epa07733612 A handout photo made available by Iranian state-run IRIB News Agency on 22 July 2019 shows crew members of the British-flagged tanker Stena Impero, that was seized by Iran in the Strait of Hormuz on 19 July 2019. Iranian Revolutionary Guard Corps (IRGC) claims to have seized Stena Impero at the Strait of Hormuz with 23 crew on board on 20 July 2019. EPA/IRIB NEWS AGENCY / HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES IRIB NEWS AGENCY / HANDOUT EPA/IRIB News Agency In photos: British-flagged tanker seized by Iran A satellite image of the Iranian port city of Bandar Abbas reveals the presence of the seized British oil tanker, the Stena Impero on July 22 Maxar Technologies/Reuters In photos: British-flagged tanker seized by Iran A speedboat of the Iran's Revolutionary Guard moves around a British-flagged oil tanker Stena Impero AP In photos: British-flagged tanker seized by Iran epa07733614 A handout photo made available by Iranian state-run IRIB News Agency on 22 July 2019 shows crew members of the British-flagged tanker Stena Impero, that was seized by Iran in the Strait of Hormuz on 19 July 2019. Iranian Revolutionary Guard Corps (IRGC) claims to have seized Stena Impero at the Strait of Hormuz with 23 crew on board on 20 July 2019. EPA/IRIB NEWS AGENCY / HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES IRIB NEWS AGENCY / HANDOUT EPA/IRIB News Agency In photos: British-flagged tanker seized by Iran In this photo released by state-run IRIB News Agency, which aired on Monday, July 22, 2019, shows cooks in the galley of the British-flagged tanker Stena Impero that was seized by Tehran in the Strait of Hormuz on Friday. The Associated Press cannot independently verify the condition of the crew members, but in the video they looked to be in good health and it didn't appear as though they were being filmed under duress. (IRIB News Agency via AP) AP In photos: British-flagged tanker seized by Iran epa07733619 A handout photo made available by Iranian state-run IRIB News Agency on 22 July 2019 shows crew members of the British-flagged tanker Stena Impero, that was seized by Iran in the Strait of Hormuz on 19 July 2019. Iranian Revolutionary Guard Corps (IRGC) claims to have seized Stena Impero at the Strait of Hormuz with 23 crew on board on 20 July 2019. EPA/IRIB NEWS AGENCY / HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES IRIB NEWS AGENCY / HANDOUT EPA/IRIB News Agency In photos: British-flagged tanker seized by Iran epa07733613 A handout photo made available by Iranian state-run IRIB News Agency on 22 July 2019 shows crew members of the British-flagged tanker Stena Impero, that was seized by Iran in the Strait of Hormuz on 19 July 2019. Iranian Revolutionary Guard Corps (IRGC) claims to have seized Stena Impero at the Strait of Hormuz with 23 crew on board on 20 July 2019. EPA/IRIB NEWS AGENCY / HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES IRIB NEWS AGENCY / HANDOUT EPA/IRIB News Agency In photos: British-flagged tanker seized by Iran epa07733616 A handout photo made available by Iranian state-run IRIB News Agency on 22 July 2019 shows crew members of the British-flagged tanker Stena Impero, that was seized by Iran in the Strait of Hormuz on 19 July 2019. Iranian Revolutionary Guard Corps (IRGC) claims to have seized Stena Impero at the Strait of Hormuz with 23 crew on board on 20 July 2019. EPA/IRIB NEWS AGENCY / HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES IRIB NEWS AGENCY / HANDOUT EPA/IRIB News Agency

Travel visas - for trips to the United Nations, for example - would be considered on a case-by-case basis, the Trump administration said.

The UN's General Assembly takes place in September.

In recent months, relations between the US and Iran have deteriorated rapidly - tankers have been attacked in the Gulf, which the US has blamed on Iran, meanwhile an air-strike was planned then aborted by Donald Trump after a US drone was downed by Iran's military.

Mr Trump is open to talks with Iran, according to agency reports, but the administration does not see Mr Zarif as a key decision maker.

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