Iran may have dealt a "fatal blow" to chances of reviving the 2015 Iran nuclear deal by removing International Atomic Energy Agency monitoring equipment, the agency's director general Rafael Grossi said.
It leaves a window of opportunity of three to four weeks to restore at least some of the monitoring that is being scrapped, or the IAEA will lose the ability to piece together Iran's most important nuclear activities, he said.
"I think this would be a fatal blow (to reviving the deal)," Mr Grossi said of what would happen if that window went unused.
Iran spoke of retaliation if the IAEA's 35-nation board of governors passed a resolution drafted by the US, France, Britain and Germany criticising Tehran for its continued failure to explain uranium traces found at undeclared sites.
The resolution was passed by a large majority late on Wednesday.
A confidential IAEA report to member states on Thursday evening seen by Reuters said IAEA inspectors had removed cameras at two sites and placed them in storage under IAEA seals there.
'Not on death watch'
US officials, speaking on condition of anonymity, said even after the three or four-week period, Iran could still provide additional information to allow for the nuclear deal's revival.
"We are not on death watch (for the next) three to four weeks," said a senior US official.
The official said the deal could be resurrected, although the longer Iran withheld access the more transparency it would have to give the IAEA.
Indirect talks between Iran and the US on reviving the 2015 deal have been stalled since March.
"You think we would retreat from our positions if you pass a resolution at the (IAEA) board of governors? In the name of God and the great nation of Iran, we will not back off a single step from our positions," Iranian President Ebrahim Raisi said.
Since then-president Donald Trump pulled Washington out of the deal and re-imposed sanctions against Tehran in 2018, Iran has breached many of the deal's limits on its nuclear activities. It is enriching uranium to close to weapons-grade.
Western powers said it is getting closer to being able to sprint towards making a nuclear bomb. Iran denies wanting to.
France, Britain and Germany, the so-called E3, condemned Iran's actions on Thursday and urged it fully resumes its co-operation with the watchdog and end its nuclear escalation.
"These actions only aggravate the situation and complicate our efforts to restore full implementation of the JCPoA. They also cast further doubt on Iran’s commitment to a successful outcome," the E3 said in a statement that did not include the US, like on Wednesday.
Washington issued a separate statement, stopping short of condemning Iran's actions and urging Iran to choose diplomacy and de-escalation.
Iran has been keeping the data recorded by the extra monitoring equipment since February of last year, meaning the IAEA can only hope to access it at a later date. Mr Grossi said it was not clear what would happen to that data now.
He said more than 40 IAEA cameras would keep operating as part of the core monitoring in Iran that predates the 2015 deal.