TEHRAN (Reuters) – Iran has resumed building centrifuges that Washington says are intended to enrich uranium to weapons-grade for use in atomic warheads, Foreign Minister Kamal Kharrazi said Saturday.

Iran’s decision backtracks from a pledge made last year to the European Union’s “big three” — Britain, France and Germany — to suspend enrichment-related activities.

“We have started building centrifuges,” Kharrazi told a news conference.

WASHINGTON (Reuters) – Iran, intensifying a standoff over its nuclear programs, has told European officials it will not back down on its right to proceed with uranium enrichment, a senior U.S. official says.

“The British and the French tell us Iran insists it will not back down on its right to proceed with enrichment,” the official, speaking on condition of anonymity, told Reuters on Friday.

During a meeting in Paris on Thursday that included Germany, the three European delegations responded that halting uranium enrichment was fundamental to a deal negotiated with Tehran last October, the U.S. official said.

The Europeans added that “nothing else was coming if Iran didn’t get back on the road to suspension, leading to cessation of enrichment and reprocessing,” the American said.

The European Union trio have given no details of their high-level talks with Iran.

But a French spokesman said in Paris on Friday that they would push ahead with talks on Iran’s nuclear

program, even though Washington says a U.N. Security Council showdown is becoming increasingly

likely.

The European Union three secured promises from Iran last October to suspend all uranium enrichment-related activities in exchange for sharing peaceful nuclear technology.

But Iran, which says it has only peaceful nuclear ambitions, was infuriated last month by a tough rebuke from the U.N. nuclear watchdog agency — the International Atomic Energy Agency (IAEA) — over

cooperation with its inspectors.

Even before the meeting in Paris, Iran said it would resume the manufacture, assembly and testing of

enrichment centrifuges, which can be used to enrich uranium for weapons.

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The United States says Iran is trying to develop nuclear weapons, a charge Tehran denies.

U.S. officials with access to intelligence estimates say Iran can achieve a bomb in three to five years,

although some experts say it might even be sooner.

The IAEA has uncovered many potentially weapons-related activities in Iran, but no clear proof that Washington is right about Iran — no “smoking gun.”

Another U.S. official, speaking anonymously, said the Europeans were “not too happy” with the Iranian

meeting.

“The EU three underscored their concerns and said (to the Iranians), ‘Look, you’re making a big mistake. You need to get back on the program,” the U.S. official said.

The Iranians “pushed back. … The fact that Iran just decided to back off of its commitment took them by

surprise and they weren’t happy about it,” he added.

Secretary of State Colin Powell repeated on Thursday that Iran had not met its IAEA obligations or kept its commitments to the EU three.

A U.N. Security Council referral was now “more and more likely,” he said during a visit to Kuwait.

The administration has been agitating to bring Iran before the security council, which can impose sanctions on violators of the Nuclear Non-proliferation Treaty.

Iran has fiercely resisted the move.

So have the EU three and other security council members, who instead have kept the matter before the IAEA as they tried to persuade Tehran to adhere to NPT and IAEA commitments.

In interviews with Reuters this week, U.S. officials for the first time said that as they move to increase

pressure on Tehran, they do not see imposing sanctions as the first goal.

The comments suggested an attempt by Washington to dampen international resistance to bringing the

controversial nuclear issue before the security council.