The agreement between the Islamic republic and six major powers had provided for the lifting of sanctions in exchange for stringent checks on Tehran's nuclear programme and guarantees that it could not seek to acquire a nuclear weapon.

The text also contains a "snapback" mechanism that could be triggered in case of "significant non-performance" of its commitments by Iran.

This would allow the United Nations Security Council to reimpose all the sanctions it had imposed between 2006 and 2015 over Tehran's nuclear activities.

The administration of United States President Donald Trump last year attempted to trigger the mechanism, but the move was rejected, as the US had unilaterally withdrawn from the nuclear deal in 2018.

"From the outset, (Iran's supreme leader Ali Khamenei) was against this snapback mechanism, which was designed against his wishes," said key Khamenei diplomatic advisor Ali Akbar Velayati in an interview published on Khamenei's website.

"In the coming negotiations, this mechanism will certainly need to be abandoned, because it's absurd."

The nuclear deal has come close to collapse since the withdrawal of the United States, which under Trump has adopted a hardline policy of "maximum pressure" against Iran, reimposing crushing US sanctions that have devastated the Iranian economy.

In response, Tehran has rolled back most of its key commitments under the accord, arguing that it is permitted to do so under the deal in light of US moves.

US President-elect Joe Biden, who takes office on January 20, says he wants to rejoin the pact.

But Khamenei insisted last week that "we are in no rush" to see the US rejoin the accord, demanding that the US first remove all the sanctions it had imposed or reinstated since 2018.

Tehran has ruled out a full overhaul of the deal, but says the US rejoining it must be the result of further negotiations.