The UN nuclear watchdog said on February 23 that it is "deeply concerned" that Iran secretly kept "undeclared nuclear material" at an "undeclared location" as the agency warned that Tehran continued to exceed "many limits" set by its 2015 nuclear deal with world powers.
The International Atomic Energy Agency (IAEA) also confirmed in a pair of reports that Iran was already enriching uranium up to 20 percent purity, and that its enriched-uranium stockpile had reached 14 times the limit established by the 4-year-old Joint Comprehensive Plan Of Action (JCPOA).
"The agency is deeply concerned that undeclared nuclear material may have been present at this undeclared location and that such nuclear material remains unreported by Iran under its safeguards agreement," the IAEA said.
Iran "has yet to provide answers" on the discovery of "anthropogenic uranium particles" found at two sites inspected last year.
IAEA Director-General Rafael Grossi then reiterated that Iran "needs to give answers" on the traces "in places they shouldn't be." He said the process with Tehran "has not yielded positive results for now."
The IAEA's warnings followed condemnation hours earlier by Britain, France, and Germany of Tehran's decision to abandon a snap-inspections regime and reduce transparency this week as part of a mounting standoff over the fate of the JCPOA.
Iran confirmed on February 22 that it had ended its implementation of an Additional Protocol allowing for surprise inspections of nuclear-related sites.
Iranian Supreme Leader Ayatollah Ali Khamenei also vowed "not to back down on the nuclear issue" and floated the possibility of escalating uranium enrichment to 60 percent, far above the 3.67-percent limit in the JCPOA and three times the 20 percent it announced a month ago.
Diplomatic maneuvering has intensified since Joe Biden was sworn in as U.S. president in January pledging to revive Washington's participation in the agreement, which the previous U.S. administration abandoned in 2018.
"We...deeply regret that Iran has started, as of today, to suspend the Additional Protocol and the transparency measures under the Joint Comprehensive Plan of Action," the British, French, and German foreign ministers said in a joint statement.
"We urge Iran to stop and reverse all measures that reduce transparency and to ensure full and timely cooperation with the IAEA," they added.
Reuters quoted an unnamed senior diplomat on February 23 as saying Iran is producing around 15 kilograms a month of uranium enriched to 20 percent.
Grossi has laid out details of a deal he worked out with Iranian officials last weekend to preserve some monitoring for up to three months beyond Tehran's deadline for nixing the snap inspections.
He described a system whereby data and "key activities" would be monitored and stored but not made available until after the period in question.
Iranian Foreign Minister Mohammad Javad Zarif said a recent law handed down by the hard-line parliament had gone into effect early on February 23 barring Iran from sharing surveillance footage of its nuclear facilities with the IAEA.
In a sign that the nuclear issue is further pitting hard-liners against President Hassan Rohani's administration, lawmakers in Iran's parliament on February 22 objected to the government's decision to allow the continued IAEA monitoring even under the modified regime.
The White House has said that its European allies are awaiting a response from Iran on an offer to host an informal meeting of current members of the JCPOA.
The United States and other governments have accused Iran of secretly trying to build a nuclear-weapons capability, a charge that Tehran has consistently rejected despite years of what the IAEA said was obfuscation and deception.