A new report from the UN atomic watchdog this week will provide fresh evidence of Iran's nuclear weapons drive, diplomats said Sunday, as Israel stoked speculation about a possible pre-emptive strike.

Previous International Atomic Energy Agency 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 intelligence update, which diplomats say will be circulated among IAEA members on Tuesday or Wednesday, will focus on Iran's alleged efforts towards putting radioactive material in a warhead and developing missiles.

"The report is not going to include some sort of 'smoking gun'," one Western diplomat told AFP. "But it will be an extensive body of evidence that will be very hard for Iran to refute as forgery, as they have done in the past."

Iranian officials have already seen the Vienna-based IAEA's information, diplomats told AFP, and Foreign Minister Ali Akbar Salehi said in comments published in Iran on Sunday that it was based on "counterfeit" claims.

IAEA head Yukiya Amano said in September's report he was "increasingly concerned" about the "possible military dimension" of Iran's atomic activities, including those "related to the development of a nuclear payload for a missile."

In May the agency listed seven areas of concern such as equipment and instrumentation for testing explosives over long distances, possibly underground, and "modelling studies" on arming a Shahab-3 missile with a nuclear payload.

The new intelligence, expected in an annex of the main Iran report, will include satellite imagery of a suspected nuclear installation at the Parchin military site 30 kilometres (20 miles) from Tehran, diplomats said.

According to analysts, Tehran has a fleet of ballistic missiles under development, the most capable of which has a range long enough to reach US bases in the Middle East, and Israel, fired from deep within Iran.

Western envoys hope the new IAEA report will help convince other countries to pile more pressure on the Islamic republic, which has been hit with four rounds of sanctions by the UN Security Council.

But Russia and China are unconvinced on the need for more action, diplomats say, with Moscow even going so far as to call openly on the IAEA not to release the report, saying it "may hinder the start of serious negotiations."

It is therefore unclear what resolution, if any, the IAEA's 35-nation board will adopt when it meets on November 17-18, with options including referral to the Security Council or setting Iran a new deadline.

"Would it be worth it to again divide the board on this issue, and also divide the E3+3?," asked Oliver Thraenert of the German Institute for International and Security Affairs, meaning the Security Council permanent members and Germany.

"To me that would not make much sense, although much will depend on the exact language of the report," he told AFP.

In either case, the release of the IAEA report comes at a time of growing speculation that Israel might launch a military strike in an attempt to knock out its arch-foe's nuclear activities.

Israeli daily Haaretz reported last week that Prime Minister Benjamin Netanyahu was seeking cabinet backing for a military strike, and that the new UN watchdog report would have a "decisive" influence.

"The possibility of a military attack against Iran is now closer to being applied than the application of a diplomatic option," Israeli President Shimon Peres warned on Sunday.

"I don't think that any decision has already been made, but there is an impression that Iran is getting closer to nuclear weapons."

In June 1981, Israeli planes bombed and destroyed an uncompleted French nuclear reactor in Iraq, and in 2007 it destroyed a suspected covert nuclear reactor in the Syrian desert.

Washington, whose relations with Tehran soured further last month over an alleged plot to kill the Saudi ambassador to the United States, has said that while the focus is on a diplomatic solution, all options are still on the table.

French Foreign Minister Alain Juppe said Sunday that sanctions should be toughened and that "everything must be done" to avoid a military conflict.