A Saudi Arabia-led coalition intervened in Yemen's civil war in 2015, backing government forces fighting Iran-allied Houthi rebels. Saudi Arabia and Iran compete for influence across the Middle East, from Syria to Iraq.
"The UN Special Envoy Martin Griffiths has arrived in Tehran for a two-day visit, during which he will meet with Iranian officials," state TV said.
Griffiths' office said the visit was part of his diplomatic efforts to support a negotiated political solution to the conflict. His immediate priority was to support agreement between the warring parties on a ceasefire, urgent humanitarian measures and a resumption of the political process, it said in a press release.
Griffiths' spokeswoman, Ismini Palla, said the visit had been planned for some time, adding it comes at a time when he is trying to bring together more diplomatic, regional and international support to his efforts to end the war.
On Saturday, Iran welcomed President Joe Biden's move on Thursday to end Washington's support for offensive operations in the Saudi-led military campaign in Yemen as a "step towards correcting past mistakes."Reversing one of former President Donald Trump's most criticized last-minute decisions, Washington also said on Friday it intended to revoke a terrorist designation for the Houthi movement in response to the humanitarian crisis in Yemen, where the United Nations says some 80% of the population is in need.