The United States and Iran opened high-stakes talks on Tehran's nuclear programme, with President Donald Trump threatening military action if they fail to produce a deal.
The two sides entered "indirect" talks - via an intermediary - in the Omani capital Muscat, Iran's foreign ministry said on Saturday.
The Americans had called for the meetings to be face-to-face.
Disagreement over the format indicated the task faced by long-term adversaries, who are seeking a new nuclear deal after Trump pulled out of an earlier agreement during his first term in 2018.
Foreign Minister Abbas Araghchi is leading the Iranian delegation, while Trump's special envoy, Steve Witkoff, heads the US team.
"Our intention is to reach a fair and honourable agreement from an equal position," Araghchi said in a video posted by Iranian state TV.
Tehran has agreed to the meetings despite baulking at Trump's "maximum pressure" campaign of ramping up sanctions and repeated military threats.
Meanwhile, the US, hand-in-glove with Iran's arch-enemy Israel, wants to stop Tehran from ever getting close to developing a nuclear bomb.
Iran and the US meet in Oman for high-level talks aimed at resolving the long-standing nuclear issue, with the potential for conflict if no agreement is reached.
Open to 'compromise'
Witkoff told The Wall Street Journal earlier that "our position today" starts with demanding that Iran completely dismantle its nuclear programme- a view held by hardliners around Trump that few expect Iran would ever accept.
"That doesn't mean, by the way, that at the margin we're not going to find other ways to find compromise between the two countries," Witkoff told the newspaper.
"Where our red line will be, there can't be weaponisation of your nuclear capability," he added.
The talks were revealed in a surprise announcement by Trump as he met the press alongside Israeli Prime Minister Benjamin Netanyahu at the White House on Monday.
Hours before they begin, Trump told reporters aboard Air Force One: "I want Iran to be a wonderful, great, happy country. But they can't have a nuclear weapon."
Iranian supreme leader Ali Khamenei's adviser Ali Shamkhani said Tehran was "seeking a real and fair agreement", adding that "important and implementable proposals are ready".
Saturday's contact between the two sides, which have not had diplomatic relations for decades, follows repeated threats of military action by both the United States and Israel.
"If it requires military, we're going to have military," Trump said on Wednesday when asked what would happen if the talks fail to produce a deal.
Responding to Trump's threat, Tehran said it could expel United Nations nuclear inspectors, a move that Washington warned would be an "escalation".
A senior adviser to Iran’s Supreme Leader warns that US aggression would leave Iran with no option but to pursue nuclear weapons for defence.
