A US intelligence official said claims by Israeli Prime Minister Benjamin Netanyahu that a secret warehouse in Tehran contained nuclear “equipment and material” were “somewhat misleading,” Reuters reported Friday.

The prime minister said in his speech to the UN General Assembly Thursday that the IAEA, the UN’s nuclear watchdog, had failed to take any action after he revealed in April a nuclear archive that Israeli spies managed to spirit out of Iran, and so he was now disclosing what he said was another “secret atomic warehouse” in the Turquzabad district of Tehran, a few miles from the archive.

Netanyahu claimed the warehouse was used for “storing massive amounts of equipment and material from Iran’s secret weapons program,” which was quickly being moved to other parts of the city.

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He claimed some 15 kilograms (33 pounds) of radioactive material had been recently removed from this atomic warehouse and squirreled away around Tehran, endangering the capital’s residents. The site may contain as much as 300 tons of nuclear-related equipment and material in 15 shipping containers, he added.

The unnamed US intelligence source was quoted by Reuters as challenging Netanyahu’s claims about the warehouse.

The prime minister’s claims were “somewhat misleading,” the source was quoted as saying. “First, we have known about this facility for some time, and it’s full of file cabinets and paper, not aluminum tubes for centrifuges, and second, so far as anyone knows, there is nothing in it that would allow Iran to break out of the JCPOA [the Iran nuclear deal] any faster than it otherwise could.”

Another anonymous official told the news agency that the US knew about the facility, which he described as “a warehouse” which housed “records and archives” from Iran’s nuclear program.

However, a State Department official called on the International Atomic Energy Agency to investigate Netanyahu’s claims.

In a statement quoted by Reuters, the official said it was “absolutely imperative that the IAEA fully exercise its authorities in order to provide confidence to the international community that there are no undeclared nuclear materials or activities in Iran.”

An unnamed US diplomatic source quoted by Israel’s national broadcaster Kan said: “The latest revelation of nuclear documents requires the Agency to find out if Iran is hiding nuclear materials or activity.”

In April, Israel announced it had smuggled out of Iran more than 100,000 documents from a Tehran archive detailing the country’s nuclear program.

Iran denied Netanyahu’s Thursday claims about a nuclear warehouse.

Iranian Foreign Minister Mohammad Javad Zarif suggested in a tweet Thursday that Netanyahu was throwing stones from a glass house, and ridiculed his use of props and oversized display boards.

No arts & craft show will ever obfuscate that Israel is only regime in our region with a *secret* and *undeclared* nuclear weapons program – including an *actual atomic arsenal*. Time for Israel to fess up and open its illegal nuclear weapons program to international inspectors. — Javad Zarif (@JZarif) September 27, 2018

“No arts & craft show will ever obfuscate that Israel is only regime in our region with a *secret* and *undeclared* nuclear weapons program — including an *actual atomic arsenal*,” Zarif said. “Time for Israel to fess up and open its illegal nuclear weapons program to international inspectors.”

Israel is widely believed to have a nuclear arsenal but has never publicly acknowledged it.

Zarif further called Netanyahu’s accusation an “obscene charge,” the state-run IRNA news agency reported Friday, and branded the Israeli prime minister a “liar who would not stop lying.”

Meanwhile, Tehran’s foreign ministry spokesman Bahram Qasemi said, “The world will only laugh loudly at this type of false, meaningless and unnecessary speech,” according to a Reuters translation of a Fars news report.

Michael Bachner and agencies contributed to this report.