Iran’s Foreign Minister Mohammad Javad Zarif, the urbane, US-educated architect of its 2015 nuclear deal with world powers, announced his resignation unexpectedly on Monday through Instagram.
"Many thanks for the generosity of the dear and brave people of Iran and its authorities over the past 67 months," he wrote on his Instagram page, jzarif_ir.
"I sincerely apologise for the inability to continue serving and for all the shortcomings during my service. Be happy and worthy."
He gave no specific reasons for his decision.
Mr Zarif played Iran's lead role in striking the deal under which Tehran agreed to curbs on its nuclear programme in return for the lifting of international financial sanctions.
He came under attack from anti-western hardliners in Iran after the US pulled out of the agreement last May and reimposed sanctions.
A spokesman for the Iranian mission to the UN, Alireza Miryousefi, confirmed the announcement of the resignation, but there was no immediate word on whether President Hassan Rouhani would accept it.
Born in 1960, Mr Zarif lived in the US from the age of 17 as a student in San Francisco and Denver, and later as a diplomat to the UN in New York, where he served as Iranian ambassador from 2002 to 2007.
He was appointed minister of foreign affairs in August 2013 after Mr Rouhani won the presidency in a landslide on a promise to open up Iran to the outside world.
Since taking charge of Iran’s nuclear talks with major powers in late 2013, Mr Zarif has been summoned to Parliament several times by hardline politicians to explain about the negotiations.
In February 2014 he caused an uproar with public comments condemning the Holocaust and was summoned to Parliament. Holocaust denial has been a staple of public speeches in Iran for decades.
Some hardliners even threatened Mr Zarif with bodily harm after the nuclear deal was signed. Iran’s top authority, Supreme Leader Ayatollah Ali Khamenei, guardedly supported the deal.
