The United States Wednesday put forward a draft resolution to the UN Security Council seeking backing for a historic deal curtailing Iran's nuclear program as a first step for international approval of the accord.

The draft text seeks formal UN endorsement for the hard-won, ground-breaking agreement reached in Vienna on Tuesday after 18 straight days of talks which capped almost two years of momentous negotiations.

The new resolution would also replace the existing framework of seven sets of Security Council sanctions imposed since 2006 on Iran, enshrining a new set of restrictions.

"We have now formally introduced this Iran resolution into the Security Council," a US diplomat said.

Under the deal, hammered out by six world powers and Iran, a web of sanctions will be gradually lifted as Tehran takes steps to dismantle and mothball much of its nuclear program to ensure it cannot build a bomb.

A vote on the resolution could come as early as Monday or Tuesday, a diplomat said.

But a UN embargo on conventional arms sales and exports is to stay in place for five years, while trade in ballistic missiles capable of being armed with a nuclear warhead will remain for eight years.

- 'There is no uncertainty' -

The draft resolution should pass with little difficulty since the five veto-wielding permanent members of the UN Security Council -- Britain, China, France, Russia and the United States -- were among those countries which negotiated the Vienna accord.

"It was negotiated. All of them know and supported every element of it. There is no uncertainty," a US official familiar with the dossier said.

The draft text was put forward by the US ambassador to the United Nations, Samantha Power during closed door talks on Wednesday.

In order to lift the sanctions, the UN's nuclear watchdog, the International Atomic Energy Agency, will have to report that Iran is meeting its commitments under the deal, and that it has fully answered concerns that prior to 2003, and perhaps later, it may have sought nuclear arms.

However, the deal also sets out a so-called "snapback" mechanism to put the old sanctions back in place. It establishes a joint commission which would examine any complaints if world powers feel Iran has not met its commitments under the Vienna deal.

If a protest is made via the joint commission, then the UN Security Council would have to vote on whether to continue the sanctions lifting.

"It seems counterintuitive, but if we veto that resolution, sanctions will snapback and all the past resolutions would come back into force," the diplomat said.

Once the UN Security Council resolution is agreed, that will start the clock ticking on the first deadline known as Adoption Day, some 90 days after the UN endorses the agreement.

Under the deal, all parties from that day must begin to make the necessary legal and administrative preparations to implement the full deal later on.