Foreign Office minister Andrew Murrison will call for “urgent de-escalation” of flared tensions between the US and Iran when he holds talks with the Tehran government on Sunday.
The trip was announced after Donald Trump said the US was “cocked and loaded” to retaliate against Iran for downing an American drone.
The strikes were reportedly called off 10 minutes before they were to be carried out on Thursday after Mr Trump was told 150 people could die.
On Saturday, a spokesman for Iran’s armed forces warned that a military strike would “set the region ablaze and burn up the US, its interests, and its allies”.
Iran cannot have Nuclear Weapons! Under the terrible Obama plan, they would have been on their way to Nuclear in a short number of years, and existing verification is not acceptable. We are putting major additional Sanctions on Iran on Monday. I look forward to the day that…..
— Donald J. Trump (@realDonaldTrump) June 22, 2019
Mr Trump later tweeted that the US will impose “major additional sanctions” on Iran on Monday after opting to halt military action “from going forward at this time”.
Dr Murrison’s visit amid the bellicose exchanges between Washington and Tehran is part of the UK’s “ongoing diplomatic dialogue with Iran”, the Foreign and Commonwealth Office (FCO) said.
“At this time of increased regional tensions and at a crucial period for the future of the nuclear deal, this visit is an opportunity for further open, frank and constructive engagement with the government of Iran.
“Dr Murrison will call for urgent de-escalation in the region and raise UK and international concerns about Iran’s regional conduct and its threat to cease complying with the nuclear deal to which the UK remains fully committed.”
Mr Trump pulled out of a long-term deal struck with Iran in 2015 to limit its sensitive nuclear activities and allow in international inspectors in return for the lifting of economic sanctions.
The deal was signed by his predecessor Barack Obama along with the UK, France, China, Russia and Germany, which still support the agreement.
But Mr Trump declared it a “terrible” deal and imposed more sanctions.
On Saturday, German chancellor Angela Merkel called for a “political solution” on Iran, saying such a result “should not just be a hope, but it should be worked towards with the utmost seriousness”.
Tensions between the US and Iran have increased in recent weeks amid claims by Washington that Tehran has been behind attacks on oil tankers the Persian Gulf.
Dr Murrison’s visit also takes place amid continuing tension between London and Tehran over the treatment of Nazanin Zaghari-Ratcliffe, a British-Iranian dual citizen who has been detained in Iran since April 2016 accused of spreading propaganda against Iran.
Her husband Richard Ratcliffe is on day eight of a hunger strike outside the Iranian Embassy in London in support of his wife who is also on hunger strike.
Speaking about Dr Murrison’s planned visit to Iran, Mr Ratcliffe told the Press Association: “I’ve been asked how hopeful I am. I’m not sure if I’m hopeful, but certainly will be watching very closely to see how things develop and what comes back.”
He said: “It’s good that the minister’s going over there. It’s good that Iran and the UK are talking. It is good if they can find a way to solve this as quickly as possible.
“The more tension there is generally in the region the harder it is for a case like Naz to be solved and that’s true always.”
Meanwhile, Etihad Airways has become the latest airline to announce it is suspending operations through Iranian airspace over the Straits of Hormuz and the Gulf of Oman.
In a statement, the United Arab Emirates-based carrier said it will use alternative flight paths on a number of routes to and from Abu Dhabi “until further notice”.