TEHRAN, Aug 29, 2025 (BSS/AFP) - Iran said Thursday the decision by European powers to trigger a mechanism reimposing sanctions under a moribund 2015 nuclear deal would undermine Tehran's cooperation with the United Nations nuclear watchdog. 

"This decision by the three European countries will seriously undermine the ongoing process of interaction and cooperation between Iran and the International Atomic Energy Agency (IAEA)," the foreign ministry said in a statement, calling the move a "provocative and unnecessary escalation".

Britain, France and Germany -- known as the E3 -- triggered the so-called "snapback" mechanism after weeks of warnings, citing Iran's continued non-compliance with its commitments under the 2015 nuclear agreement.

The move took place just days after Iranian and European diplomats held talks in Geneva, the second since Israel and the United States attacked its nuclear facilities during a 12-day war between Iran and Israel this year. 

In an earlier phone call with his European counterparts, Foreign Minister Abbas Araghchi said Tehran would respond "appropriately to this illegal and unjustified action ... in order to protect and guarantee its national rights and interests," according to a statement from his ministry.

He called on the three countries to "appropriately correct this wrong decision in the coming days".

While Araghchi did not specify what measures Iran might take, Tehran has previously warned that such a move could lead to the exclusion of the European powers from any future negotiations on Iran's nuclear programme.

On Wednesday Iran's deputy foreign minister Kazem Gharibabadi said that if the snapback was triggered, "the path of interaction that we have now opened with the International Atomic Energy Agency will also be completely affected and will probably stop". 

He made the remarks following the return of IAEA inspectors to Iran to oversee fuel replacement operations at the key nuclear facility in Bushehr, in the country's southwest. 

It was the first IAEA team to arrive since Iran suspended cooperation with the agency over the agency's failure to condemn the Israeli and US strikes. 

Tehran has since said that future cooperation with the agency will take "a new form".

The 12-day war with Israel has also derailed nuclear talks between Tehran and Washington that had begun in April with the aim of reaching a deal to replace the failed 2015 accord. 

The 2015 deal was torpedoed in 2018 when Donald Trump, during his first term as president, unilaterally withdrew the United States and slapped crippling sanctions on Iran.