By John Irish and Humeyra Pamuk
PARIS/WASHINGTON (Reuters) - The United States and the European countries party to the Iran nuclear deal pushed back on Wednesday against Tehran's decision to enrich uranium at 60% purity, with the top U.S. diplomat calling the move "provocative" and questioning Iran's seriousness about talks.
Iran has said it will enrich uranium to 60% - a big step closer to the 90% that is weapons-grade material - in response to what it says was an act of sabotage by Israel against its key nuclear facility last week.
U.S. Secretary of State Antony Blinken said Tehran's intent raised questions about its seriousness over the talks in Vienna between Iran and the world powers to revive the 2015 nuclear accord.
"We take very seriously its provocative announcement of an intent to begin enriching uranium at 60 percent," Blinken told a news conference at NATO headquarters in Brussels. "I have to tell you the step calls into question Iran's seriousness with regard the nuclear talks," he said.
The nuclear deal has unravelled as Iran has breached its limits on uranium enrichment in a graduated response to the U.S. withdrawal from the pact in 2018 and Washington's reinstatement of harsh economic sanctions against the Islamic Republic.
Last week, Iran and fellow signatories held what they described as "constructive" talks to restore the deal ditched by the Trump administration - which saw the terms as too lenient on Tehran.
The explosion at Iran's uranium enrichment site came on Sunday ahead of a second week of talks. Israel, which supported former U.S. President Donald Trump's hard line against Iran, has not formally commented on the incident at Iran's Natanz site, which appeared to be the latest twist in a long-running covert war.
Britain, France and Germany also said Tehran's new decision to enrich at 60 %, from the 20% it has reached so far, and activate 1,000 advanced centrifuge machines at its Natanz plant was at odds with the talks. They said they rejected "all escalatory measures by any actor", in an apparent signal to Israel.
"Iran's announcements are particularly regrettable given they come at a time when all JCPoA participants and the United States have started substantive discussions, with the objective of finding a rapid diplomatic solution to revitalise and restore the JCPoA," the three countries said in a statement, referring to the 2015 deal.
"Iran’s dangerous recent communication is contrary to the constructive spirit and good faith of these discussions," it said of the talks, which resume between Iran and global powers in Vienna on Thursday, aimed at salvaging the accord.
A U.S. official, speaking on condition of anonymity, said the events of the past week had not necessarily made things easier. "But I am not going to speculate as to whether it means that we can’t reach a deal … We wouldn’t be going if we thought that it was over, but I am not going to say that we expect a breakthrough.”
STAND OFF
In an apparent rebuff later on Wednesday, Iranian Supreme Leader Ayatollah Ali Khamenei said the United States was trying to impose its terms for rescuing the deal and European powers were doing Washington's bidding.
"The nuclear talks in Vienna must not become talks of attrition...This is harmful for our country," Khamenei, who has the last word on Iranian matters of state, was quoted as saying by state television.
Biden took office in January with a commitment to rejoin the deal if Tehran returns to full compliance with its restrictions on enrichment. Tehran has repeatedly said that all sanctions must be rescinded first.
"We have already declared Iran's policy. Sanctions must be removed first. Once we are certain that has been done, we will carry out our commitments," Khamenei said, according to semi-official Tasnim news agency.
"The offers they provide are usually arrogant and humiliating and are not worth looking at."
Iran has "almost completed preparations" to launch 60% enrichment and has notified the International Atomic Energy Agency that it will activate 1,024 more IR-1 centrifuges, its older first generation of the machines at Natanz, the U.N. nuclear watchdog said later on Wednesday.
Iran's leading Gulf foe Saudi Arabia also weighed in on Wednesday, saying it believed any revival of the nuclear deal should be a starting point for further talks that include regional states to expand the accord.
Rayd Krimly, head of policy planning at the Saudi foreign ministry, told Reuters any deal that fails to effectively address the security concerns of countries in the region would not work, and Riyadh was consulting with the global powers.
"We want to make sure at a minimum that any financial resources made available to Iran via the nuclear deal are not used...to destabilise the region," he said.
Iran’s deal with the six powers caps the fissile purity to which it can refine uranium at 3.67%. That is well under the 20% achieved before the agreement, and far below the 90% suitable for a nuclear weapon.