Britain has backed a “vitally important” nuclear deal with Iran, after Israel and the US accused the Iranians of pursuing atomic weapons.
Israel claimed it had evidence showing Iran covertly sought nuclear weapons – an accusation rejected by Iran.
The US said Israel’s claims are “consistent” with its own intelligence.
Six nations signed an accord in 2015 lifting sanctions on Iran in exchange for the Iranian’s abandoning a nuclear weapon programme.
Iran said it only sought nuclear energy, not weapons.
A British government spokesman said inspectors appointed as part of the accord are providing a “vitally important way of independently verifying that Iran is adhering to the deal”.
The spokesman added: “We have never been naive about Iran and its nuclear intentions.”
Britain, Germany and France all still support the accord, which was also signed by China and Russia.
On Monday Israeli Prime Minister Benjamin Netanyahu revealed what he said were “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 responded that Israel’s revelations were a “childish” stunt to influence President Donald Trump’s decision on whether to remain in the nuclear deal, which he is due to make by 12 May.
Mr Trump has asked the European signatories to the agreement to “fix the terrible flaws” with it or he will refuse to extend sanctions relief on Iran.
In a statement, the White House said Israel’s information provided “new and compelling details” about Iran’s alleged efforts to develop “missile-deliverable nuclear weapons”.
The US statement said: “These facts are consistent with what the US has long known – Iran has a robust, clandestine nuclear weapons program that it has tried and failed to hide from the world and from its own people.”
According to Iranian state TV, Ali Akbar Salehi, the head of the country’s Atomic Energy Organisation, said he hoped Mr Trump “comes to his senses and stays in the deal”.