That deal effectively bought time as the United States, European powers and Tehran try to salvage the 2015 nuclear agreement that has been on the brink of collapse since Donald Trump withdrew from it.

Tehran now demands that Washington scrap punishing sanctions Trump reimposed in 2018, while Washington demands that Iran first return to all its nuclear commitments.

In the standoff, Iran's conservative-dominated parliament has demanded that Iran from Tuesday limit some inspections by the International Atomic Energy Agency (IAEA).

IAEA chief Rafael Grossi held last-ditch talks in Tehran on Sunday where the two sides hammered out a temporary technical deal.

They confirmed that Iran will continue to allow access to UN inspectors to its nuclear sites -- but will for three months bar inspections of other, non-nuclear sites.

Grossi said afterwards that a "temporary solution" had been reached with Tehran that enables the IAEA to retain "a necessary degree of monitoring and verification work".

Iran's foreign ministry spokesman Saeed Khatibzadeh said Monday the talks had "resulted in a very significant diplomatic achievement and a very significant technical achievement".

Khatibzadeh stressed that the outcome was "within the framework of the parliament's binding law".

Iran will temporarily suspend so-called "voluntary transparency measures" -- notably inspections of non-nuclear sites, including military sites suspected of nuclear-related activity.

Tehran will for "three months record and keep the information of some activities and monitoring equipment" at such sites, Iran's Atomic Energy Organization said.

This means that cameras will keep running at those sites, "but no footage will be given to the IAEA," Khatibzadeh said.

If the US sanctions are not lifted within three months, the footage will be deleted, Iran's atomic body has said.