The chief of the UN's nuclear watchdog will travel to Washington next week to meet lawmakers and discuss a historic deal struck with Iran earlier this month, the Vienna-based agency said on Friday.

Yukiya Amano was due to meet members of the US Senate Committee on Foreign Relations on Wednesday," the International Atomic Energy Agency announced in a statement.

"Mr Amano welcomed an invitation letter he received from the Senators early on July 31, and will meet with them on August 5 to discuss the IAEA's role in verifying and monitoring nuclear-related measures under the Joint Comprehensive Plan of Action," the agency said, in reference to the accord reached on July 14.

The so-called P5+1 -- Britain, France, Germany Russia, China and the United States -- signed an agreement with Iran aimed at ensuring Tehran does not acquire a nuclear bomb, in return for relief from crippling sanctions.

As part of the deal, the IAEA will have to verify that Iran does indeed scale down its facilities, clearing a path towards ending UN, US and EU sanctions.

The White House has mounted an intense lobbying campaign to convince members of the Republican-controlled Congress to back the deal.

The Senate and House of Representatives have until September to review the agreement, before taking a vote on whether to approve it.

Mr Amano is likely to face scrutiny from sceptical senators who argue that the deal will essentially legitimise Iran as a nuclear threshold state.

Many Republicans and some Democrats have voiced concern that the accord could trigger a regional nuclear arms race, embolden and strengthen Iran and put key US ally Israel in jeopardy.

Wise-cracking US celebrities endorse Iran deal
Washington (AFP) July 31, 2015 - Morgan Freeman, Jack Black and a host of other celebrities star in a video backing Americas' nuclear deal with Iran, wise-cracking their way through an often surreal mixture of Hollywood, politics and diplomacy.

The video uploaded this week onto YouTube comes as President Barack Obama's administration tries to sell the agreement to the public and a sceptical Congress.

Washington and five world powers reached an accord earlier this month with Iran that reins in the Islamic republic's nuclear program in exchange for an easing of crippling economic sanctions.

The video starts with a joke comparing nuclear war to being "toasted."

"Most people think toast is delicious, this would not be that kind of toast," Black points out.

The Hollywood cast is then joined by other figures including Jordan's Queen Noor, retired US ambassador Thomas Pickering and former CIA officer Valerie Plame, to explain details of their Iran deal endorsement.

"Look, it is true that if Congress sabotages this deal there would be nothing stopping Iran from getting the bomb," Pickering says.

The video presents war as a likely alternative to the deal.

Plame, whose identity as a spy was leaked in 2003, engages with the comics to drive the point home.

"I don't think you need a surrealistic food metaphor to comprehend the sheer recklessness of a war with Iran," Plame said.

"Once a war begins, the chances of Iran developing a nuclear weapon would only increase," she said before a joke with Black about her revealed identity.

"The agreement currently on the table is the best way to ensure Iran doesn't build a --- bomb," the Oscar-winning Freeman said, with the expletive bleeped out.