A sixth round of Iran-US nuclear talks is planned for Sunday, Tehran has said, as the two sides appear locked in a standoff over uranium enrichment nearly two months into high-stakes negotiations.
It came as European powers and the United States submitted a censure motion to the UN's nuclear watchdog in an effort to ramp up pressure on Iran, despite Tehran's warnings.
Iran has said it will present a counter-proposal to the latest draft from Washington, which it criticised for failing to offer sanctions relief in return for curbs on its nuclear programme.
"The next round of Iran-US indirect talks is being planned for next Sunday in Muscat," Iranian foreign ministry spokesman Esmaeil Baqaei said in a statement on Tuesday.
There was no immediate comment from mediator Oman, which has hosted some of the previous rounds, while Washington has said the talks could be held as early as Thursday.
The two sides have held five rounds of negotiations since April, the highest level of contact since President Donald Trump withdrew Washington from a 2015 nuclear accord during his first term.
Trump has said the next meeting is expected on Thursday, although a source familiar with preparations said it would more likely be on Friday or Saturday.
Iran's top negotiator, Foreign Minister Abbas Araghchi, will be attending the annual Oslo Forum in Norway on Thursday, his office said.
On 31 May, after the fifth round of talks, Iran said it had received "elements" of a US proposal for an agreement, which Araghchi criticised for its "ambiguities".
Tehran has said the offer failed to include issues raised in previous negotiations, including the lifting of sanctions — a key demand for Tehran, which has been reeling under their weight for years.
On Monday, Foreign Ministry spokesperson Baqaei said Iran would present a "reasonable, logical and balanced" counter-proposal.
'National interests'
Trump said the next round of talks could make it clear whether a nuclear deal is possible to avoid military action.
In a key sticking point, Tehran has defended its right to enrich uranium as "non-negotiable", while Washington called any Iranian enrichment a "red line".
Iran currently enriches uranium to 60 percent, far above the 3.67 percent limit set in the 2015 deal and close, though still short of the 90 percent needed for a nuclear warhead.
Western countries, including the United States and its ally Israel, have long accused Iran of seeking to acquire atomic weapons, while Tehran insists its nuclear programme is for peaceful purposes.
