TEHRAN, Iran (AP) -- Iran started to shut down its most sensitive nuclear work on Monday, part of a landmark deal struck with world powers that ease international concerns over the country's nuclear program and clearing the way for a partial lifting of sanctions, the state media said.
The United Nations nuclear agency, the International Atomic Energy Agency, confirmed that higher-level uranium enrichment in the Natanz facility in central Iran had been stopped.
Iran's decision to halt higher-level enrichment is seen as a key step toward easing Western fears over Tehran's nuclear program. The West fears Iran seeks to build a nuclear bomb. The Islamic Republic insists the program is solely for peaceful purposes.
The shutdown follows a historic deal reached Iran reached with world powers in Geneva on Nov. 24 that calls for an end to higher-level enrichment in exchange for the lifting of some economic sanctions.
Iranian state TV said authorities halted enrichment of uranium to 20 percent by disconnecting the cascades of centrifuges enriching uranium at the facility. That level is just steps away from bomb-making materials.
The broadcast said international inspectors were on hand to witness the stoppage before leaving to monitor the suspension of enrichment at Fordo, another uranium enrichment site in central Iran.
The official IRNA news agency said Iran also started Monday to convert part of its stockpile of 20 percent enriched uranium to oxide, which can be used to produce nuclear fuel but is difficult to reconvert for weapons use.
Under the Geneva deal, Iran agreed to halt its 20 percent enrichment program but continue enrichment up to 5 percent. It also agreed to convert half of its stockpile of 20 percent enriched uranium to oxide and dilute the remaining half to 5 percent over a period of six months.
In addition to the enrichment measures, the six-month interim deal also commits Iran to opening its nuclear program to greater U.N. inspections and providing more details on its nuclear activities and facilities. Iran will also refrain from commissioning its under-construction 40 megawatt heavy water reactor in Arak, central Iran.
The U.S., European Union and other world powers are studying the U.N. nuclear agency report, said U.S. State Department deputy spokeswoman Marie Harf. She said the U.S. would have further comment "after all parties have had the opportunity to review the report."
In exchange for the nuclear curbs, Iran receives a halt to new sanctions and easing of existing sanctions. Measures targeting petrochemical products, gold and other precious metals, the auto industry, passenger plane parts and services will be lifted immediately.
The Geneva deal allows Iran to continue exporting crude oil in its current level, which is reported to be about 1 million barrels a day.
In Brussels, foreign ministers from the 28 European Union members, gathered for one of their periodic consultations, were poised to suspend some sanctions for six months if U.N. inspectors report that Iran's uranium enrichment efforts have halted.
The ministers will hear a report from EU foreign policy chief Catherine Ashton, who chaired the Geneva negotiations that led to the agreement with Tehran. Miroslav Lajcak, the Slovak foreign minister, told reporters as the meeting opened that "we are moving in a good direction. That means we are ready to lift sanctions."
The sanctions have weakened Iran's economy, and an easing of the measures could provide relief to ordinary Iranians.
Senior officials in U.S. President Barack Obama's administration have put the total relief figure at some $7 billion of an estimated $100 billion in Iranian assets in foreign banks. Iran is to receive the first $550 million installment of $4.2 billion of its assets blocked overseas on Feb. 1.
British Foreign Secretary William Hague emphasized that only some sanctions would be suspended once it is clear Iran had ceased enrichment.
"Of course other sanctions will be maintained. This is limited and proportionate sanctions relief," he said. "Then we will get to work at a very early stage, as early as next month, on the negotiation for a comprehensive deal to settle the Iranian nuclear issue."
Vice President Ali Akbar Salehi said Iran has a total of 196 kilograms of 20 percent enriched uranium and will convert half of it to oxide over a period of six months, 15 kilograms each month. Iran, he said, will dilute the remaining half to under 5 percent level within three months.
Iran's hard-liners have called the deal a "poisoned chalice", highlighting the difficult task President Hasan Rouhani faces in selling the accord to skeptics.
Hard-line media denounced the planned halt. The Vatan-e-Emrooz daily printed in black Monday instead of its usual colors, a sign of sorrow and mourning. It declared the deal a "nuclear holocaust" and called it a gift to Israel's Prime Minister Benyamin Netanyahu.
"Today, Netanyahu is the happiest person in the world," it said. However, the Israeli prime minister has made the opposite argument as the hard-liners: He says the deal gives Iran too much for too few concessions.
The interim Geneva accord will last for six months as Iran and the world powers negotiate a final deal. Foreign Minister Mohammad Javad Zarif told reporters Saturday that Tehran is ready to enter talks for a permanent accord as soon as the interim deal goes into force.
AP writer John-Thor Dahlburg in Brussels contributed to this report.