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