TEHRAN (AP) — As Iran started to shut down its most sensitive nuclear work on Monday, the White House praised the “concrete actions” that represent “an important step forward.”

“These actions represent the first time in nearly a decade that Iran has verifiably enacted measures to halt progress on its nuclear program, and roll it back in key respects,” said press spokesman Jay Carney in a statement released Monday. “Iran has also begun to provide the IAEA with increased transparency into the Iranian nuclear program, through more frequent and intrusive inspections and the expanded provision of information to the IAEA.”

Carney also pledged that America “will today follow through on our commitment to begin to provide the modest relief agreed to with Iran. At the same time, we will continue our aggressive enforcement of the sanctions measures that will remain in place throughout this six-month period.”

The action by Iran comes as part of a landmark deal struck with world powers, easing concerns over the country’s nuclear program and clearing the way for a partial lifting of sanctions, Tehran and the UN said.

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.”

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.

The US, European Union and other world powers are studying the UN nuclear agency report, said US State Department deputy spokeswoman Marie Harf. She said the US would have further comment “after all parties have had the opportunity to review the report.”

An Iranian state TV broadcast said authorities halted enrichment of uranium to 20 percent, just steps away from bomb-making materials, by disconnecting the cascades of centrifuges enriching uranium in Natanz.

“Production of 20 percent enriched uranium has been halted by cutting the links feeding cascades in this facility,” it said. The IAEA report confirmed that the centrifuges were disconnected.

The broadcast said international inspectors were present Monday when Iran began implementing its obligations under the historic deal reached in Geneva on November 24, 2013. They left to monitor the suspension 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 to produce nuclear fuel.

The landmark measures ease Western fears over Iran’s contested nuclear program, and are expected to lead to the lifting of some sanctions in return. Senior officials in US 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 February 1.

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 UN 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.”

Under the historic deal, Iran agreed to halt its 20 percent enrichment program but will 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 UN 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.

In return, it 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.

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.

The US and some of its allies fear that Iran may finally be able to build an atomic weapon. Iran has denied the charges, saying its nuclear program is for peaceful purposes such as electricity and producing medical isotopes to treat cancer patients.

Copyright 2014 The Associated Press.