Washington DC - Iran has agreed to dilute its enriched uranium stocks under its interim deal with the US, senior US administration officials said Wednesday as they released what they said was the text of the agreement.

"The fact that they're conceding to that is a major, major win for the United States of America," one of the US officials said of the nuclear issue on a call with reporters.

The deal would also reopen the Strait of Hormuz and allow Iranian oil sales, while the US and its allies would also make plans for a $300 billion reconstruction fund for Iran.

The US officials read out the wording on a conference call after days of uncertainty about what was actually included in the deal that President Donald Trump announced on Sunday.

The outline deal will be followed by 60 days of negotiations on a final accord – after which Trump said Washington could simply go back to "bombing" if Iran doesn't agree.

Iran's nuclear program is mentioned in the deal, according to the US officials, with extra clauses compared to drafts of the agreement that were leaked in US and foreign media.

Under the text read out by US officials, the two countries agreed to discuss a mechanism for dealing with Iran's stocks of enriched uranium, which have been at the center of US allegations that Tehran wants to develop nuclear arms.

It says that the "minimum methodology" would be "down-blending on site under the supervision of the IAEA" – the International Atomic Energy Agency.

Down-blending involves mixing enriched uranium that can be refined to make atomic bombs with depleted uranium, to reduce its radioactivity.

"They're saying we will destroy the enriched stockpile, and this is how we're going to do it at a minimum," the senior US official said, in what he said was his own commentary on the deal.

The US officials acknowledged that the possible $300 billion reconstruction fund for Iran following the war launched by Israel and the US on February 29 was the "second most controversial" part after the nuclear issue.

The text says that Washington "undertakes with regional partners to develop a definitive mutually agreed plan with at least $300 billion for the reconstruction and economic development of the Islamic Republic of Iran."

The mechanism for that would also be part of the 60-day talks.

But the official insisted Washington would not be on the hook, with Trump facing charges of hypocrisy after harshly criticizing cash paid out to Iran under President Barack Obama's 2015 nuclear deal.

"Note that it doesn't require us to do anything...to ever pay a cent of money to the Iranians, to ever contribute money to this reconstruction fund," the first senior official said.

"What it says is that if we get to a final deal and if the Iranians behave, we will permit the sanctions relief that would allow, for example, the Emiratis to build a power plant in Iran."