Israeli Prime Minister Benjamin Netanyahu has revealed what he says are "secret nuclear files" proving Iran once covertly pursued nuclear weapons.

He said thousands of pages of material obtained by Israel showed Iran had deceived the world by denying it had ever sought nuclear weapons.

Iran agreed in 2015 to curb its nuclear energy programme in return for the lifting of sanctions.

It maintained that it had only been pursuing nuclear energy.

But Mr Netanyahu accused Iran of conducting a secret weapons programme until 2003 codenamed "Project Amad". He claimed Iran continued to pursue nuclear weapons knowledge after Project Amad was shuttered.

Iran pushed back against the claims. Foreign Minister Javad Zarif tweeted to say the evidence was a "rehash of old allegations" which had already been dealt with by the United Nations nuclear watchdog.

Iran's foreign minister accused Mr Netanyahu of a "childish" stunt to influence President Donald Trump's decision on whether to remain in a nuclear deal with Iran.

The US along with five other international powers struck a deal with Iran in 2015 to curb the country's nuclear programme.

Mr Trump, who has long threatened to scrap the Obama-era deal, said he had viewed part of Mr Netanyahu's presentation and said the situation was "not acceptable".

He said he would make a decision on whether to retain the deal on or before 12 May.

A White House statement said there were "new and compelling details" in Mr Netanyahu's material.

"These facts are consistent with what the United States has long known: Iran has a robust, clandestine nuclear weapons programme that it has tried and failed to hide from the world and from its own people," the statement went on.

However, European powers have said they are committed to upholding the accord.

"We have never been naive about Iran and its nuclear intentions," said a UK government spokesperson late on Monday.

"That is why the IAEA inspection regime agreed as part of the Iran nuclear deal is one of the most extensive and robust in the history of international nuclear accords."

Mr Netanyahu said he had spoken to the leaders of France and Germany about Israel's intelligence and planned to send representatives to the two countries to discuss it.

A German government spokesman said the country would carry out a detailed analysis of Israel's intelligence, Reuters reported.

John Hughes, a former deputy director for sanctions at the US State Department who worked on the Iran deal, said he had not seen anything in the Israeli presentation that would change the deal.

"I think, frankly, this was a political statement meant to try to influence President Trump's decision on whether to pull out of the deal," Mr Hughes said. "I think it's mostly recycled material."