Tehran said Washington was not sure how and through what mechanisms the sanctions would be lifted.

Iran asked the United States to clarify exactly how sanctions will be lifted if the two sides want to reach a new agreement on Tehran's nuclear program.

Foreign Ministry spokesman Esmail Baghaei commented a few days after the U.S. submitted an "acceptable" proposal. The unverified report claims that Iran regards the proposal as a “non-starter” and is ready to reject the proposal.

The two have been negotiating seven weeks on nuclear plans, and the United States seeks assurances that it is peaceful, while Iran hopes to escape punishments from sanctions suffered by its economic distress in recent years.

But Tehran now asks Washington to detail what it provides, reflecting suspicions published by Supreme Leader Ayatollah Ali Khamenei earlier this year.

Baghaei stressed in a speech delivered by the official IRNA news agency that there is a need to ensure “real sanctions”, including detailed information on “how and what mechanisms to pass.”

"The United States has not yet provided the necessary clarity in this regard," he said.

Baha'i also reiterated Iran's intention to continue to enrich uranium for the purpose of "peace".

U.S. envoy Steve Witkoff said President Donald Trump opposes Tehran's continued any abundance, calling it a "red line."

The leaked UN report shows that Iran has increased its uranium production to 60%, much lower than about 90% required for atomic weapons, but significantly higher than about 4% required for power generation.

Baghaei dismissed the report because it was biased, accusing unnamed Western countries of putting pressure on the UN to oppose Iran's interests.

Official sources quoted by the New York Times said the recent U.S. proposals include calls for Iran to end all calls for fulfilling.

Although Tehran has confirmed the acceptance of the proposal, which the White House describes as Iran's "best interest", it said it is still reviewing the document.

"Receiving the text certainly does not mean accepting it, nor does it mean it is acceptable," Baghaei said.

Reuters quoted an unnamed Iranian diplomat as saying that Tehran is "drafting a negative reaction to the U.S. proposal, which could be interpreted as rejection."

The report said the proposal described it as a “non-starter” because it would not mitigate the U.S. “clear explanation” of its rich position or offer sanctions relief.

Since April 12, Iran has held five rounds of dialogue with the United States to seek a new deal to replace the leading power Trump abandoned during his first term in 2018.