Western officials believe Israel may have leaked information from IAEA investigation in bid to raise global pressure on Tehran

Israel is suspected of carrying out a series of leaks implicating Iran in nuclear weapons experiments in an attempt to raise international pressure on Tehran and halt its programme.

Western diplomats believe the leaks may have backfired, compromising a UN-sanctioned investigation into Iran's past nuclear activities and current aspirations.

The latest leak, published by the Associated Press (AP), purported to be an Iranian diagram showing the physics of a nuclear blast, but scientists quickly pointed out an elementary mistake that cast doubt on its significance and authenticity. An article in the Bulletin of the Atomic Scientists declared: "This diagram does nothing more than indicate either slipshod analysis or an amateurish hoax."

The leaked diagram raised questions about an investigation being carried out by International Atomic Energy Agency (IAEA) inspectors after it emerged that it formed part of a file of intelligence on alleged Iranian nuclear weapons work held by the agency.

The IAEA's publication of a summary of the file in November 2011 helped trigger a new round of punitive EU and US sanctions.

Western officials say they have reasons to suspect Israel of being behind the most recent leak and a series of previous disclosures from the IAEA investigation, pointing to Israel's impatience at what it sees as international complacency over Iranian nuclear activity.

The leaks are part of an intensifying shadow war over Iran's atomic programme being played out in Vienna, home to the IAEA's headquarters.

The Israeli spy agency, the Mossad, is highly active in the Austrian capital, as is Iran and most of the world's major intelligence agencies, leading to frequent comparisons with its earlier incarnation as a battleground for spies in the early years of the cold war.

The Israeli government did not reply to a request for comment and AP described the source of the latest leak only as "officials from a country critical of Iran's atomic programme".

An "intelligence summary" provided to AP with the graph appeared to go out of its way to implicate two men in nuclear weapons testing who had been targeted for assassination two years ago. One of them, Majid Shahriari, was killed on his way to work in Tehran in November 2010 after a motorcyclist fixed a bomb to the door of his car. The other, Fereydoun Abbasi-Davani, was wounded in a near identical attack the same day.

A book published earlier this year by veteran Israeli and American writers on intelligence, called Spies Against Armageddon, said the attacks were carried out by an assassination unit known as Kidon, or Bayonet - part of the Mossad.

One western source said the "intelligence summary" supplied with the leaked diagram "reads like an attempt to justify the assassinations".

According to one European diplomat, however, the principal impact of the leak would be to compromise the ongoing IAEA investigation into whether Iran has tried to develop a nuclear weapon at any point. "This is just one small snapshot of what the IAEA is working on, and part of a much broader collection of data from multiple sources," the diplomat said.

"The particular document turns out to have a huge error but the IAEA was aware of it and saw it in the context of everything it has. It paints a convincing case."

Sources who have seen the documents said the graph was based on a spreadsheet of data in the IAEA's possession which appears to analyse the energy released by a nuclear blast. The mistake was made when that data was transposed on to a graph, on which the wrong units were used on one of the axes.

There is widespread belief among western governments, Russia, China and most independent experts that evidence is substantial for an Iranian nuclear weapons programme until 2003. There is far less consensus on what activities, if any, have been carried out since. The IAEA inquiry has so far not found a "smoking gun".

Analysts say that the recent leaks may have shown the IAEA's hand, revealing what it knows and does not know, and therefore undermined the position of its inspectors in tense and so far fruitless talks with Iranian officials about the country's past nuclear activities.

Iran rejects the evidence against it as forged and has not granted access to its nuclear scientists or to a site known as Parchin where IAEA inspectors believe the high-explosive components for a nuclear warhead may have been tested.

The IAEA says it has evidence that the site is being sanitised to remove any incriminating traces of past experiments.

David Albright, a nuclear expert at the Institute for Science and International Security in Washington, said he had no knowledge of who was behind the leak but added: "Whoever did this has undermined the IAEA's credibility and made it harder for it to do its work."

The next round of IAEA talks with Iran will take place on Saturday in Tehran. The US has said that if Iran does not co-operate with the IAEA investigation by March, the matter should be referred to the UN security council.

The security council has repeatedly demanded that Iran suspend enrichment of uranium until it has satisfied the international community that it is not pursuing a covert weapons programme. Iran has rejected the demand, insisting its programme is entirely peaceful, and has intensified its enrichment effort, triggering Israeli threats of military action.

A new round of negotiations between Iran and six world powers, aimed at trading curbs on enrichment for sanctions relief, is due to begin in the next few weeks but no date has been set.