The UN Security Council on Monday unanimously endorsed the landmark nuclear deal between Iran and six world powers and authorized a series of measures leading to the end of UN sanctions that have hurt Iran's economy.

But the measure also provides a mechanism for UN sanctions to "snap back" in place if Iran fails to meet its obligations.

Both U.S. Ambassador Samantha Power and Iran's UN Ambassador Gholamali Khoshroo called the agreement an important achievement for diplomacy, the Iranian promising to be "resolute in fulfilling its obligations" and the American pledging to be vigilant in ensuring they are carried out.

The resolution had been agreed to by the five veto-wielding council members, who along with Germany negotiated the nuclear deal with Iran. It was co-sponsored by all 15 members of the Security Council. The European Union's foreign ministers endorsed the agreement later Monday in Brussels and pledged to implement it.

Under the agreement, Iran's nuclear program will be curbed for a decade in exchange for potentially hundreds of billions of dollars' worth of relief from international sanctions. Many key penalties on the Iranian economy, such as those related to the energy and financial sectors, could be lifted by the end of the year.

Iran insists its nuclear program is purely peaceful, aimed at producing nuclear energy and medical isotopes, but the United States and its Western allies believe Tehran's real goal is to build atomic weapons. U.S. President Barack Obama has stressed that all of Iran's pathways to a nuclear weapon are cut off for the duration of the agreement and Iran will remove two-thirds of its installed centrifuges and get rid of 98 per cent of its stockpile of uranium.

Britain's U.N. Ambassador Matthew Rycroft said "the world is now a safer place in the knowledge that Iran cannot now build a nuclear bomb." But Israel's UN Ambassador Ron Prosor told reporters immediately after the vote that the Security Council had "awarded a great prize to the most dangerous country in the world," calling it "a very sad day" not only for Israel but the entire world.

The document specifies that seven resolutions related to UN sanctions will be terminated when Iran has completed a series of major steps to curb its nuclear program and the International Atomic Energy Agency has concluded that "all nuclear material in Iran remains in peaceful activities."

All provisions of the U.N. resolution will terminate in 10 years, including the "snap back" provision on sanctions.

But last week the six major powers -- the U.S., Russia, China, Britain, France and Germany -- and the European Union sent a letter, seen by The Associated Press, informing UN Secretary-General Ban Ki-moon that they have agreed to extend the snap back mechanism for an additional five years. They asked Ban to send the letter to the Security Council.

Obama told reporters the vote will send a strong message of international support for the agreement as the best way to ensure "that Iran does not get a nuclear weapon." He faces strong opposition in the Republican-controlled Congress and expressed hope that members will pay attention to the vote.

Power, the U.S. ambassador, said the nuclear deal doesn't change the United States' "profound concern about human rights violations committed by the Iranian government or about the instability Iran fuels beyond its nuclear program, from its support for terrorist proxies to repeated threats against Israel to its other destabilizing activities in the region."

She urged Iran to release three "unjustly imprisoned" Americans and to determine the whereabouts of Robert Levinson, a former FBI agent who vanished in Iran in 2007.

The message that diplomacy can work ran through many speeches from council members.

Iran's Khoshroo stressed that only if commitments are fully honoured "can diplomacy prevail over conflict and war in a world that is replete with violence, suffering and oppression."

Russia's UN Ambassador Vitaly Churkin said the agreement "clearly demonstrates that where there's a political will based on realism and respect for legitimate mutual interests of the international community, the most complex tasks can be resolved."

"Today, the Security Council has confirmed the inalienable right of Iran to develop its peaceful nuclear program, including to enrich uranium, while ensuring the comprehensive control by the IAEA," Churkin said.