Iran "hasn't abandoned its goal to develop nuclear weapons," Benjamin Netanyahu told the UN General Assembly, where his annual appearance has frequently focused on Israel's chief enemy, the Islamic republic.

"Israel will never let a regime that calls for our destruction to develop nuclear weapons. Not now, not in 10 years, not ever," he said. "Israel will do whatever it must do to defend itself against Iran's aggression."

"What Iran hides, Israel will find," the prime minister added.

Israel bitterly opposes the Iran nuclear deal, brokered by the United States, Russia, China and European nations in 2015 and has congratulated President Donald Trump for walking away from the deal.

Netanyahu opened his speech by claiming that Iran had a secret atomic warehouse in Tehran, holding up a map and a photograph of an outwardly "innocent looking compound" which he urged the UN atomic agency to inspect.

"Today I'm disclosing for the first time that Iran has another secret facility in Tehran, a secret atomic warehouse for storing massive amounts of equipment and material from Iran's secret nuclear weapons program," he said.

He also claimed that Hezbollah had positioned three missile sites near Beirut airport, holding up what he called "a picture worth a thousand missiles" and titled "Beirut Precision Guided Missile."

Netanyahu accused Iranian agents of plotting attacks in the United States and Europe, as well as being an aggressor in the Middle East.

He accused the Iranian regime of brutally oppressing its own people for four decades, and of waging violence in Iraq and Syria, arming Hezbollah in Lebanon, financing Hamas in Gaza and firing missiles into Saudi Arabia.

He tore into Europe for its policy of "appeasement" with Iran, a word that evokes in history European capitals' reluctance to stand up against Adolf Hitler in the run-up to World War II.

"Have these European leaders learnt nothing from history? Will they ever wake up?" Netanyahu hectored. "We in Israel don't need a wake-up call because Iran threatens us every day."

He said Israel was "deeply grateful" to the Trump administration for withdrawing from the Iran deal, an agreement which he claimed had had the "unintended consequence" of bringing Israel closer to its Arab neighbors.

"By empowering Iran, it brought Israel and many Arab states closer together than ever before ... in an intimacy and friendship that I've not seen in my lifetime and would have been unimaginable a few years ago."