Iran's Supreme Leader Ayatollah Ali Khamenei said on Tuesday that the country's future should not be tied to the success or failure of nuclear talks with world powers, noting that talks to revive the 2015 nuclear deal were "going well."

Khamenei added - in front of Iranian officials, including Iranian President Ebrahim Raisi - "Do not let your work be disrupted, whether the negotiations reach positive, semi-positive or negative results."

Khamenei stressed that the United States broke its promises when it withdrew from the nuclear agreement, and has now reached a dead end, while Iran is not in this same situation, calling on Iranian nuclear negotiators to resist excessive American demands.

Last Sunday, Iranian Foreign Minister Hossein Amir Abdollahian accused the United States of seeking to "put new conditions" during the Vienna talks, without further details.

On Monday, Iran expressed doubts about the "will" of the United States to reach an understanding to revive the agreement on its nuclear program concluded in 2015, citing continuing differences after a year of negotiations between Tehran and the six great powers.

In recent weeks, negotiations appeared to be making progress, and some negotiators went so far as to announce an imminent agreement.

But there are still differences, especially over the issue of removing the Iranian Revolutionary Guard from the US blacklist of "foreign terrorist organizations" that was included under former President Donald Trump.

Under Trump, Washington withdrew from the nuclear deal in 2018, and reimposed economic sanctions on Iran.

A year later, Iran began violating restrictions on its nuclear program under the 2015 agreement. The agreement aims to make the development of a nuclear bomb more difficult for Iran.

Iran says its nuclear program is for peaceful use only.