Secretary of State John Kerry will this week defend an emerging deal intended to curb Iran's nuclear ambitions, urging skeptical US lawmakers not to put up obstacles that could scupper the tough negotiations.

"I'll lay out the facts," Kerry told CBS's "Face the Nation" on Sunday when asked about a different narrative emerging from Iranian leaders about the outlines of a deal agreed in Lausanne, Switzerland earlier this month.

"Everything I have laid out is a fact. And I'll stand by them."

The Lausanne framework marked a major breakthrough in a 12-year standoff between Iran and the West, which disputes Tehran's denial that it is seeking to acquire nuclear bomb.

Global powers must resolve a series of difficult technical issues by a June 30 deadline for a final deal, including the steps for lifting global sanctions imposed on Iran, and lingering questions over the possible military dimensions of its nuclear program.

"I think people need to hold their fire and let us negotiate without interference and be able to complete the job over the course of the two-and-a-half months," Kerry said.

The State Department angered Iran when it released a fact sheet on April 2 about the Lausanne outlines, which appeared to differ from the Iranians' understanding of what had been agreed.

Iran's Supreme leader Ayatollah Ali Khamenei, who will have the final say on any deal, plunged the accord into doubt last week suggesting that "nothing is binding" while President Hassan Rouhani demanded that sanctions be immediately lifted when any deal is signed.

Global powers -- Britain, China, France, Germany, Russia and the United States -- have said sanctions will only be gradually eased and want a mechanism to ensure they can be swiftly reimposed if Iran breaks its word.

"We had this same duelling narratives, discrepancies, spin, whatever you want to call it with respect to the interim agreement" reached in November 2013, Kerry said.

- 'Delusional' -

But he insisted that Iran had complied with the interim deal freezing parts of its nuclear program in exchange for limited sanctions relief.

Kerry, however, has come under fire from US lawmakers, including his former Republican Senate friend and adversary John McCain who last week said America's top diplomat was "delusional."

"I think you're going to find out that they never agreed to the things that John Kerry claimed they had," McCain told a radio show on Thursday, adding that Kerry was now trying to "sell a bill of goods hoping that maybe the Iranians wouldn't say much about it."

Kerry refused to be drawn into a tit-for-tat argument with McCain.

"What we're looking for is not to have Congress interfere with our ability, inappropriately, by stepping on the prerogatives of the executive department of the president, and putting in place conditions and terms that are going to get in the way of the limitation of a plan," Kerry told NBC's "Meet the Press."

But President Barack Obama on Saturday lept to Kerry's defense.

Suggesting America's top diplomat was "somehow less trustworthy in the interpretation of what's in a political agreement than the supreme leader of Iran -- that's an indication of the degree to which partisanship has crossed all boundaries," Obama told reporters in Panama.

Obama said he could understand that people might not trust Iran, which has not had diplomatic ties with the United States since the 1979 storming of the US embassy in Tehran.

But "actively communicating that the United States government and our secretary of state is somehow spinning presentations in a negotiation with a foreign power, particularly one that you say is your enemy, that's a problem. It needs to stop."

French Foreign Minister Laurent Fabius meanwhile agreed Sunday that "there remains work to do" to reach a final deal after talks in Saudi Arabia.

Iran must end 'aggression' for sanctions relief: Netanyahu
Jerusalem (AFP) April 12, 2015 - Israeli Prime Minister Benjamin Netanyahu said Sunday Iran should have to end its "aggression in the region" to win relief from sanctions, taking another swipe at a framework nuclear agreement.

World powers agreed with Iran last week on the framework of a deal to be signed by the end of June to rein in its nuclear programme in exchange for the lifting of international sanctions.

Iranian President Hassan Rouhani on Thursday called for the sanctions to be totally lifted on the same day that the deal is implemented.

But Netanyahu, whose government has repeatedly denounced the framework agreement as an "historic mistake", said any such move should be linked to other issues.

"Instead of lifting the restrictions on Iran's nuclear facilities and programme at a fixed date, a better deal would link the lifting of these restrictions to an end of Iran's aggression in the region, its worldwide terrorism and its threats to annihilate Israel," he said in a statement.

Earlier, Netanyahu warned the Islamic republic could not be trusted.

"To my regret, all of the things I warned about vis-a-vis the framework agreement that was put together in Lausanne are coming true before our eyes," Netanyahu's office quoted him as saying, referring to the Swiss city where the framework deal was agreed.

"This framework gives the leading terrorist state in the world a certain path to nuclear bombs," he said.

"How can such a country be trusted?"

Haaretz newspaper on Sunday said he had told his top officials that even full Iranian compliance with the terms of an international deal would be a ploy to lull the international community into complacency and should on no account be taken at face value.

The paper cited two senior officials as reporting his comments to an emergency meeting of his security cabinet on April 3, the day after the framework agreement was reached between Iran and world powers.

The Israeli leader had told his ministers Iran would probably "keep to every letter in the agreement," deflecting scrutiny of its nuclear programme.

"Netanyahu said at the meeting that it would be impossible to catch the Iranians cheating simply because they will not break the agreement," one of the officials was quoted as saying.

Netanyahu reportedly said that in 10 to 15 years, when the main clauses of the agreement expire, sanctions would be lifted, Iran would get a clean bill of health and then it would push ahead with its nuclear plans.

"Iran insists on maintaining its formidable nuclear capabilities with which it could produce nuclear bombs," he said in Sunday's statement.

"Iran refuses to allow effective inspections of all its suspect facilities," he said.

Israel and many Western governments suspect Iran's civilian nuclear programme is a front for efforts to build a military capability -- a charge which Tehran denies.

Israel has the Middle East's sole, albeit undeclared, nuclear arsenal.