“Evaluations regarding the absence of undeclared nuclear material and activities for Iran remain ongoing,” UN International Atomic Energy Agency (IAEA) head, Yukiya Amano said in a statement from his headquarters in Vienna.

“The Agency continues to evaluate Iran’s declarations under the Additional Protocol, and has conducted complementary accesses under the Additional Protocol to all the sites and locations in Iran which it needed to visit,” he added, referring to a series of agreements it has with Iran.

The agency chief stressed that "in line with established safeguards practices, all information obtained, including from third parties, is subject to rigorous review and assessed together with other available information to arrive at an independent assessment based on the Agency’s own expertise." He said that "the Agency's independence in relation to the implementation of verification activities is of paramount importance."

In a speech to the UN General Assembly last week Netanyahu displayed photographs taken by Israeli intelligence which he said showed a secret site in the heart of Tehran, Iran’s capital, for storing massive amounts of equipment and material for a secret nuclear weapons programme.

“I have a message to the head of the IAEA, Yukiya Amano,” he declared from the Assembly’s podium before Heads of State and Government attending the 73rd annual general debate. “I believe he’s a good man. I believe he wants to do the right thing.

“Well, Mr. Amano, do the right thing. Go inspect this atomic warehouse, immediately, before the Iranians finish clearing it out.”

Netanyahu, who from the start has opposed the 2015 accord under which Iran agreed to suspend nuclear activities in return for the lifting of sanctions (JCPOA) claimed that Iranian officials last month had already removed 15 kilogrammes of radioactive material from at least 15 “gigantic” shipping containers at the undeclared site, in an attempt “to hide the evidence” of their programme to develop nuclear weapons.

The JCPOA – reached by Iran, China, France, Germany, Russia, the United Kingdom, the US and the European Union – sets out rigorous IAEA mechanisms for monitoring restrictions placed on Iran’s nuclear programme, while paving the way for the lifting of UN sanctions against the country.