The UK has appointed an ambassador to Iran for the first time since 2011.
Nicholas Hopton has been promoted to the official title of Her Majesty’s Ambassador.
He has been British Chargé d’affaires in Tehran since the embassy was reopened a year ago, after closing in 2011.
The Foreign Office said the move marks an important step forward in the two countries’ diplomatic relations.
It follows last week’s re-introduction of a British Airways London-Tehran service after a four-year absence.
Speaking about the appointment, Foreign Secretary Boris Johnson said: "This is an important moment in the relationship between the UK and Iran.
"The upgrade in diplomatic relations gives us the opportunity to develop our discussions on a range of issues, including our consular cases about which I am deeply concerned, and which I have raised with Foreign Minister Zarif.
"I hope this will mark the start of more productive cooperation between our countries, enabling us to discuss more directly issues such as human rights and Iran’s role in the region, as well as ongoing implementation of the nuclear deal and the expansion of the trading relationship between both our countries."
Hopton was previously Her Majesty’s Ambassador to Qatar from 2013 to 2015.
He joined the Foreign Office in 1989 and has also served as ambassador to Yemen and at the British Embassies in Paris, Rome and Rabat.
