Iran has started using advanced models of centrifuges to enrich uranium, the UN’s nuclear watchdog said Thursday, in a new breach of the faltering 2015 deal with world powers.

Advanced centrifuges at Iran’s Natanz facility “were accumulating, or had been prepared to accumulate, enriched uranium,” the International Atomic Energy Agency (IAEA) said in a report seen by AFP.

Under the 2015 accord that puts curbs on Iran’s nuclear program in exchange for sanctions relief, Tehran is only meant to enrich uranium using less efficient IR-1 centrifuges.

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The landmark deal has been in jeopardy since May last year when US President Donald Trump withdrew the US from it and reimposed sanctions.

The remaining parties to the deal with Iran — Britain, China, France, Germany and Russia — have tried to salvage the accord, but Tehran has repeatedly accused Europe of not doing enough.

Iran’s supreme leader Ayatollah Ali Khamenei said on Thursday that Europeans should not be trusted, based on their inability to save the deal.

Khamenei said, “Europeans did not fulfill any of their commitments, and this is the strongest reason that they shouldn’t be trusted.”

Many parties to the nuclear deal had hoped European mediation could salvage the nuclear agreement.

But Khamenei said Europeans were as hostile toward Iran as the US, and that European mediation had provided little so far beyond “long speeches.”

Iranian President Hassan Rouhani told the UN General Assembly gathering on Wednesday that Iran would not negotiate on the issue of its nuclear program as long as sanctions remain in place.

“Our response to any negotiation under sanctions is negative,” he said of the US economic measures, adding that Iran has “resisted the most merciless economic terrorism” from a nation that is engaging in “international piracy.”

Rouhani’s highly anticipated remarks at the UN came a day after Trump described Iran as “one of the greatest threats” to the planet.

The remarks also came as the US and its allies accuse Iran of being behind a major drone-and-missile strike on Saudi Arabia’s key oil sites earlier this month. Iran has denied any involvement and says any strikes by the US or Saudi Arabia will lead to “all-out war.”

The escalating crisis has raised concerns that direct conflict, with Iran at the center, could break out in the region —- a scenario that all concerned parties, including Iran and Saudi Arabia, have stressed they want to avoid.

The United States has sent military reinforcements and beefed up its security presence in the Middle East in past months amid the rising tensions with Iran.