The United States and Europe began preparations to lift trade sanctions that have hobbled the Iranian economy as a historic nuclear deal came into effect on Sunday, 90 days after the UN Security Council endorsed the accord.

Foreign firms will not be able to resume ties with Iran's oil industry and banks right away, as sanctions will remain in place until Iran fulfills its end of the bargain.

The implementation of the sanction-lifting agreement will only occur once UN nuclear watchdog the International Atomic Energy Agency (IAEA) confirms that Iran has dramatically scaled back its nuclear program.

Iran said that the lengthy process of confirmation will probably start this week.

On Monday, envoys of the deal signatories - Britain, China, France, Germany, Russia and the United States - will meet in Vienna to form a commission to oversee the implementation of the accord.

The deal, known as the Joint Comprehensive Plan of Action (JCPOA), requires Tehran to surrender or dilute the bulk of its enriched nuclear fuel stocks, dismantle most of its centrifuges and halt operation of a reactor capable of making plutonium.

Only then will the sanctions waivers that US President Barack Obama ordered his administration to issue on Sunday come into effect, allowing trade to resume. "Today marks an important milestone toward preventing Iran from obtaining a nuclear weapon and ensuring its nuclear program is exclusively peaceful going forward," Obama said in a statement.

US Secretary of State John Kerry, who played a central role in negotiating the deal, added "If fully implemented, it will bring unprecedented insight and accountability to Iran's nuclear program forever."

The European Union has also adopted a legal framework for lifting sanctions imposed on Iran.

The accord "brings us a step closer to the beginning of implementation of the [July deal], to which we are strongly committed," EU foreign policy chief Federica Mogherini said in a joint statement with Iranian Foreign Minister Javad Zarif.

"As Iran begins taking its nuclear-related measures and the United States and our partners prepare to lift nuclear-related sanctions in response, we move one step closer to a successful JCPOA and a more secure international community," US Treasury Secretary Jack Lew said.

Ali Akbar Salehi, head of Iran's nuclear agency, was awaiting President Hassan Rouhani's order to remove thousands of centrifuges from sites at Natanz and Fordo. "What we need to accomplish is a huge task. We hope to start this week or next week," he told Iranian state television.

In addition to slashing the number of centrifuges at Natanz and Fordo to around 6,000, Iran will have to prove to the IAEA that its Arak reactor cannot be used for military purposes.