TEHRAN/WASHINGTON: Iran`s supreme leader Ayatollah Ali Khamenei said on Tuesday that nuclear talks with the United States were unlikely to yield any results, amid a diplomatic standoff over the Islamic republic`s enrichment activities.

`We don`t think it will lead to any outcome. We don`t know what will happen,` said Khamenei during a speech, adding that denying Iran`s right to enrich uranium was `a big mistake`. Khamenei added demand Washington`s demands to Tehran to stop enriching uranium are `excessive and outrageous`.

Meanwhile, US Secretary of State Marco Rubio said the Trump administration is working to reach an agreement that would allow Iran to have a civil nuclear energy programme but not enrich uranium, admitting that achieving such a deal `will not be easy.Rubio told the Senate Foreign Relations Committee that the administration was offering an `off-ramp` for Iran to pursue prosperity and peace. `It will not be easy, but that`s the process we`re engaged in now, Rubio said.

Iran and the United States have held four rounds of Omani-mediated nuclear talks since April 12, the highest-level contact between the two foes since Washington abandoned the 2015 nuclear accord.

They had confirmed plans to hold another round of discussions during their last meeting on May 11, which Iran described as `difficult but useful`, while a US official said Washington was `encouraged`.

Iran currently enriches uranium to 60 per cent, far above the 3.67pc limit set in the 2015 deal and close though still short of the 90pc needed for anuclear warhead.

Western countries, including the United States, have long accused Iran of seeking to acquire atomic weapons, while Iran insists its nuclear programme is for peaceful purposes. Iran has repeatedly insisted its right to maintain uranium enrichment was `non-negotiable`, while chief US negotiator Steve Witkoff has called it a `red line`.

On Sunday, Witkoff reiterated that the United States `cannot allow even one percent of an enrichment capability.` `The American side involved in these indirect negotiations should refrain from speaking nonsense, said Khamenei.

Earlier, Iran`s Foreign Minister and lead negotiator Abbas Araghchi said `enrichment in Iran, however, will continue with or without a deal`.-Agencies