Mr Trump has been warned he would be guilty of "genocide" if he were to follow through on a threat to "obliterate" parts of Iran.

The issue is likely to dominate the two-day G20 summit, which begins on Friday in the Japanese city of Osaka.

Amid heightened tensions between the two countries, the US president said earlier this week that he would authorise a response of "great and overwhelming force" if the Middle Eastern nation attacked "anything American" - adding that some areas would face "obliteration".

In a tweet of his own, Iranian foreign minister Javad Zarif has said Mr Trump will "endanger peace" if he continues with his aggressive rhetoric.


Image: Javad Zarif is the Iranian foreign minister

He told the Republican that "obliteration" would lead to "genocide", which he said was a war crime, and said the prospect of a "short war" with Iran was "an illusion".

"Whoever begins war will not be the one ending it," he said, adding: "Negotiations and threats are mutually exclusive".

And Tehran has said that while the US wants talks, they will not take part while the two countries are at economic loggerheads.

Mr Zarif also hit out at fresh US sanctions imposed on Supreme Leader Ayatollah Ali Khamenei and his associates, which have been described by Iranian President Hassan Rouhani as "outrageous and idiotic".

Iran has said the sanctions could spell a "permanent closure" to diplomacy between the two countries after Tehran shot down an unmanned American drone last week.

Mr Trump initially told reporters the sanctions were in response to the attack on the aircraft, but later claimed they would have been imposed regardless of the incident.

Russia has said it would counteract the sanctions on Tehran, which it has branded "illegal", and called for dialogue between the US and Iran.

'Trump hates these wars in the Middle East'

Moscow has also supported the claim from Iran that the drone was in its airspace when it was downed, and said US evidence alleging Tehran was behind attacks on US ships in the Gulf of Oman was poor and unprofessional.

British Foreign Secretary Jeremy Hunt, who is one of two contenders to be the next prime minister, has said he "can't envisage any situation" in which the UK would go to war with Iran - even if the US did.

Acting US defence secretary Patrick Shanahan has said Washington "does not seek war" with Iran, but told NATO allies that its "hostile actions" were an "international problem".

Tensions between the two countries have been rising since the US pulled out of a 2015 nuclear deal that world powers signed with Iran, and reinstated crushing sanctions on its economy.