WASHINGTON // Iran will begin to dismantle some of its nuclear programme beginning January 20 under the terms of an agreement reached with world leaders, the United States president, Barack Obama, said on Sunday, pledging to veto any Congressional efforts to impose new sanctions during the process.

The agreement marks the first time in a decade that Iran “has agreed to specific actions that halt progress on its nuclear programme and roll back key parts of the programme,” Mr Obama said, confirming a report made by Iranian officials on January 10.

Iran and the so-called P5+1 countries — China, France, Russia, the United Kingdom and the US, plus Germany — reached an accord on November 24 in Geneva that hadn’t taken effect. Under the first- step agreement, Iran will get as much as $7 billion (Dh26bn) in relief from economic sanctions over six months, the Obama administration has said.

As part of the agreement, Iran agreed to limit its enrichment capabilities and will undergo more frequent inspections of its nuclear sites, Mr Obama said on Sunday.

“Taken together, these and other steps will advance our goal of preventing Iran from obtaining a nuclear weapon,” Mr Obama said. The sanction relief will occur “so long as Iran fulfils its obligations and as we pursue a comprehensive solutions to Iran’s nuclear programme.”

Mr Obama said he would veto any legislation to impose new sanctions during the negotiations for a broader agreement.

The European Union’s foreign policy chief, Catherine Ashton, and the Iranian foreign ministry also issued statements confirming the date.

“Capitals have confirmed the result of the talks in Geneva ... the Geneva deal will be implemented from January 20,” said Marzieh Afkham, spokeswoman for the Iranian foreign ministry.

Ms Ashton said the sides would now ask the United Nations’ nuclear watchdog to verify the deal’s implementation.

“We will ask the IAEA to undertake the necessary nuclear-related monitoring and verification activities,” she said.

* Bloomberg and Reuters