Philip Hammond is to visit Iran as the UK reopens its embassy for the first time since it was attacked by a mob in 2011.
The recent nuclear deal accelerated a thaw in diplomatic relations with Tehran and opened the door to the first such visit to the country by a British foreign secretary since 2003.
A senior Government source confirmed that Mr Hammond would fly out to the country over the weekend with a delegation of business leaders and senior officials.
It is the latest in a rush of missions by his international counterparts as Western allies all seek to take advantage of the improved atmosphere.
The embassy was closed almost four years ago after it was ransacked by a mob protesting against the imposition of international sanctions.
Some will be lifted in return for assurances that Iran's nuclear programme is not aimed at producing a weapon under the deal struck by the UK and five other nations in July.
The reopening of the embassy has been plagued by technical obstacles for more than a year since it was first proposed publicly by Mr Hammond's predecessor William Hague.
Tehran's reluctance to relax import laws has slowed the replacement of communications and other equipment taken out when the post was abandoned.
It is understood that the Home Office is continuing to work with the Iranian government on restoring a full visa service but there remain outstanding issues over Iranians who have overstayed their right to be in the UK.
Re-opening the embassy could unsettle British allies such as Saudi Arabia and Israel which have poor relations with Iran.
Although Saudi Arabia has softened its stance on the July 14 deal, Israeli Prime Minister Benjamin Netanyahu remains bitterly opposed to the accord and is reportedly lobbying the US Congress to block the deal.
Last month David Cameron moved to reassure Gulf allies that the nuclear deal will not result in any lessening of pressure on Tehran over its support for terrorism and its destabilising influence in the region.
Mr Cameron said the UK and international allies "have no starry-eyed naivety" about the regime and would "remain as tough as we've always been".
At the time, the PM told Iranian president Hassan Rouhani the agreement could pave the way to closer co-operation on issues like countering the threat from the Islamic State (IS) terror group as well as reopening the embassy in Tehran.
Meanwhile, Iran loosened its restrictions on BBC journalists operating in the country earlier this month, stating that reporters would be allowed to work there for a week.
It was another sign of warming UK-Iran relations as the BBC is often vilified in the local media.