A majority of Iranian lawmakers on Sunday demanded the country's negotiators publish a "fact sheet" on a newly agreed framework nuclear accord, while denouncing details laid out in an American version.

"In a letter, members of parliament asked for the publishing of an Iranian fact sheet, and so far 212 have signed it," Javad Karimi Ghodusi, a member of the 290-seat assembly, was quoted as saying by the official IRNA news agency.

On April 2, Iran and world powers agreed on a framework accord to be finalised by the end of June to rein in Tehran's suspect nuclear programme in exchange for the lifting international sanctions.

Only one official statement with limited details was issued at the time, jointly by Iranian Foreign Minister Mohammad Javad Zarif and EU foreign policy chief Federica Mogherini.

Later on, however, the US State Department published on its website an outline of some more key issues of the framework.

Zarif criticised the US version, saying on Twitter that "the solutions are good for all, as they stand. There is no need to spin using 'fact sheets' so early on".

After every political event, "each side focuses on their own perspective of what has happened and what will happen and it is natural that each side highlights the parts that are more to their benefit," Abbas Araghchi, a top Iranian negotiator, said Thursday.

"The Americans did it in written form... and our narrative which was a real one was thoroughly expressed in Mr. Zarif's remarks. We don't intend to publish it in writing yet, but we will do so if necessary."

Another negotiator, Iranian Atomic Energy Organisation chief Ali Akbar Salehi, said the US fact sheet mixed up "truth and lies" and "it could be said that they offered their own interpretation in order to create tension in our country".

Iran's supreme leader Ayatollah Ali Khamenei, who has the final word on all matters of state, was also defiant over a final deal.

"The main problem is that from now on details must be discussed, and since the other party is unloyal, stubborn and into backstabbing, in the discussions on details they might restrict" the negotiators and Iran, he said in a speech Thursday.

New expert talks on Iran deal may start next week: US
Washington (AFP) April 13, 2015 - Expert talks to resolve the toughest issues blocking a full Iran nuclear deal could begin next week as the countdown starts to a June 30 deadline, a US official said Monday.

Secretary of State John Kerry arrived late Monday at Congress to brief skeptical House lawmakers about the outlines of a deal struck earlier this month in Lausanne.

He told reporters before the closed-door briefing open to all 435 House lawmakers that he wanted to go into "some detail because there have been a lot of ... misrepresentations."

"We hope Congress will listen carefully and ask the questions that it wants, but also give us the space and time to be able to complete a very difficult task which has high stakes for our country," Kerry added.

He will also meet Tuesday with senators seeking to stave off new legislation aimed at ensuring Congress gets to approve any final deal, as well as imposing possible new sanctions on Iran.

Republican Senator Bob Corker, who has co-sponsored a draft bill to give Congress the power to review any final deal, said he may be garnering enough support to overcome any veto by President Barack Obama.

"I think things are moving our way," Corker told CNN.

"Let's let Congress weigh in on that, and if Congress doesn't believe this is an acceptable transaction, have the opportunity for a resolution of disapproval which would stop those sanctions from being lifted."

Kerry's lead negotiator Under Secretary Wendy Sherman was meanwhile already en route for Germany and a meeting of G7 countries.

Kerry will join the G7 foreign ministers meeting in Lubeck on Wednesday, but on the sidelines Sherman will discuss with European political directors the next steps in the Iran negotiations following the April 2 breakthrough.

The framework hammered out in Lausanne after months of tough negotiations sets out the parameters for a final deal scaling back Iran's nuclear program.

But some of the toughest issues, including the lifting of global sanctions and a mechanism to put them back into place if Iran falters on the deal.

"We expect that possibly as early as next week, the experts would reconvene and start working. We don't have anything nailed down yet, though," said State Department acting spokeswoman Marie Harf.

Kerry has come under fire for pushing the deal, with many US lawmakers still wary of Iran, a long-time US foe, which has not had full diplomatic relations with Washington for some 35 years.