Iran's chief negotiator has warned the United States was not to be trusted, saying Tehran would not agree to any deal with Washington unless it fully secured Iranian rights.
Mohammad Bagher Ghalibaf's remarks came as reports emerged that US President Donald Trump had sent a tougher peace proposal back to Iran, and underlined the rift that the parties still need to close.
Any tweaks to the draft could further delay an agreement to formally end the Middle East war and reopen the Strait of Hormuz after weeks of fraught negotiations marked by sharp rhetoric and occasional flare-ups of violence.
Iran was already in talks with the US about the fate of its nuclear programme in February when the US and Israel launched air and missile strikes that wiped out much of the Islamic republic's senior leadership.
And, while Tehran has long insisted that its nuclear programme is for purely civilian ends, the United States and its Western allies suspect it aims to develop a weapon.
The New York Times and Axios reported yesterday that Mr Trump had sent back a "tougher" new framework to be considered by Iran, though details remain unclear.
Mr Trump has said his priorities include stopping Iran from developing any nuclear weapon and reopening the Hormuz shipping lane, which Iran has blockaded since the war began.
"The one guarantee that I have to have is that there will be no nuclear weapons. They've agreed to that, and it was very interesting," he told his daughter-in-law Lara Trump in an interview on her Fox News show.
Tehran, however, has previously cast doubt on Mr Trump's assertions and the sides remain far apart on key issues.
"We will not approve any agreement until we are certain that the rights of the Iranian people have been upheld," Mr Ghalibaf said in a video broadcast on state television.
According to the Tasnim news agency, exchanges on the text "are ongoing, with both parties regularly proposing amendments".
"No agreement has yet been finalised, and it is possible that any agreement will be rejected," it said.
Iran has said it needs the release of $12 billion in frozen assets before engaging in substantive talks on its nuclear programme, dismissing earlier Trump comments that its enriched uranium stockpile would be destroyed as "baseless", according to Iranian media.
Flare-ups
One of Washington's stated war aims was the destruction of Iran's ballistic missile programme, with General Dan Caine - the top US military officer - estimating in April that more than 80% of its missile facilities had been struck.
But CNN reported today that an analysis of satellite imagery showed Tehran has since been able to excavate 50 out of 69 tunnel entrances hit by US strikes at 18 underground missile sites.
Though daily strikes throughout Iran and the Gulf halted after Tehran and Washington agreed to a temporary ceasefire in April, there have been sporadic attacks.
Iran's Revolutionary Guards had shot down a US military drone "about to enter Iranian territorial waters", Iran's state broadcaster IRIB reported, though Washington has not confirmed the incident.
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Nevertheless diplomacy has continued, with Mr Trump under pressure to secure a deal that would lift competing US and Iranian blockades around the Strait of Hormuz that have strangled a vital route for global oil supplies.
After Mr Trump said Iran would charge "no tolls" on ships passing through the strait under any deal, Iranian news agency Fars cited sources saying "no such clause" existed.
Iran's ISNA news agency on Saturday quoted lawmaker Alireza Salimi as saying a plan for Iranian "management and sovereignty" over the strait - including imposing "administrative fees" - would soon go before parliament.
Tehran has insisted that any peace deal include Lebanon, where fierce fighting continues, with Beirut urging "a swift and real ceasefire" and accusing Israel of pursuing a "scorched-earth policy" as it expands operations against Iran-backed Hezbollah.
The UN Security Council will hold an emergency meeting tomorrow on the widening Israeli offensive following its capture of the strategic medieval castle of Beaufort, diplomatic sources told AFP.
