Israeli officials were tightlipped on Wednesday following the release of a damning report by the UN nuclear watchdog into Iran's controversial nuclear programme.

"We are studying the report," said an official in Prime Minister Benjamin Netanyahu's bureau without saying whether or not Israel would respond formally.

Israel's military radio said Netanyahu had ordered his ministers not to comment on the matter out of concern that any statement or Israeli move would draw international criticism and would play into Iran's hands.

But opposition leader and Kadima party chairwoman Tzipi Livni said publication of the report meant Israel should push the world to act firmly to stop Iran.

"Now that the truth has been presented to the world, Israel must galvanise the free world to stop Iran," she said in a posting on her Facebook page. "Determination and diplomatic wisdom are crucial now."

Head of the Knesset's Foreign and Defence Committee Shaul Mofaz, also a Kadima MP, said the "severe report" provided the free world with the opportunity to "take action" against Iran.

"This is the moment of truth for the Western world's foreign policy, headed by (US) President (Barack) Obama," the Iranian-born former chief of staff said late on Tuesday.

"The report should be seen as an opportunity to change the trend, and the mission is not solely Israel's."

The world must "deepen" the sanctions on Iran, to the point of paralysing its economy, he said, stressing that military action remained the last option, Mofaz told army radio on Wednesday.

"Military action in general, and specifically by Israel, is currently the last and worst option -- but all options should be on the table now," he warned.

The official silence stood in stark contrast to the chatter in Israel in recent weeks suggesting a pre-emptive strike on Iran's nuclear facilities was being seriously considered by Netanyahu and Defence Minister Ehud Barak.

At the weekend, President Shimon Peres had warned that the likelihood of an attack was becoming "more and more likely."

Haaretz newspaper quoted government officials as saying Israel was holding off from immediate comment "because it wants to evaluate the world's response to the IAEA findings and does not want to appear to be leading the international community."

The IAEA report, a copy of which was seen by AFP late on Tuesday, said the agency had "serious concerns regarding possible military dimensions" of Iran's nuclear programme, and said it had "credible" information that Tehran "has carried out activities relevant to the development of a nuclear explosive device."

In Israel, media commentators had on Tuesday suggested the "unprecedented severity" of the report meant a strike on Iran was unlikely.

Television Channels 2 and 10 both said the release of the report would give Israel "some weeks or some months" to see if the international community slaps "crippling sanctions" on the Islamic republic.

France threatens 'unprecedented' sanctions against Iran
Paris (AFP) Nov 9, 2011 - France called Wednesday for unprecedented sanctions if Iran continues to defy the world over its atomic programme after the UN nuclear watchdog said Tehran had worked on nuclear weapons technology.

"If Iran refuses to abide by the demands of the international community and rejects all serious cooperation, we are prepared to adopt, with those countries that follow, unprecedented sanctions," the foreign ministry said in a statement.

"The unprecedented report that the International Atomic Energy Agency has just published strengthens France's profound concern about Iran's nuclear programme," it said.

The ministry said that activities noted in the IAEA's report "are in violation of UN Security Council resolutions and the IAEA's governing council. They have no credible civil purpose."

The report's elements on "militarisation activities, along with the accumulation of enriched uranium and the intensive pursuit of ballistic tests paint a picture that leaves little doubt about Iran's intentions."

"All of this means that Iran has sought, and apparently continues to seek, the nuclear bomb under the cover of an alleged civilian and peaceful programme."

The IAEA's report on Tuesday said it had "serious concerns regarding possible military dimensions to Iran's nuclear programme."

"This information indicates that Iran has carried out activities relevant to the development of a nuclear explosive device," it said.

The Vienna-based agency said some of its more than 1,000 pages of information indicated Iran has done work "on the development of an indigenous design of a nuclear weapon including the testing of components."

Previous IAEA assessments have centred on Iran's efforts to produce fissile material -- uranium and plutonium -- which can be put to peaceful uses like power generation, or be used to make a nuclear bomb.

But the update focuses on Iran's alleged efforts towards putting the radioactive material in a warhead and developing missiles. Iran denies it is trying to make a nuclear bomb.

Russia and China have expressed reservations about the publication of the IAEA report and may block a fifth round of United Nations sanctions in the Security Council.