Vienna: Iran and the UN nuclear watchdog held talks Friday in a fresh push to patch up relations as Tehran feels the heat from sanctions and amid fevered speculation of imminent Israeli military action.

But with the International Atomic Energy Agency having this year failed in a string of other meetings, including in Tehran, to get Iran to address evidence that the agency has of suspected past nuclear weapons research, hopes were not high.

“I cannot say at this time that I am optimistic about the outcome of the coming meeting,” IAEA head Yukiya Amano, who went to Iran in May hoping to sign a deal but who came back empty-handed, said Wednesday.

Iran’s envoy to the IAEA, Ali Asghar Soltanieh, was characteristically upbeat as he went into the talks in Vienna, cheerily telling reporters he expected “progress” and that both sides “are trying to bridge the gap.”

Even if negotiators do make headway, they are unlikely to break the current deadlock in higher-level diplomatic efforts on a different track - between Iran and the five permanent members of the UN Security Council plus Germany - after high-profile but fruitless meetings in Istanbul, Baghdad and Moscow this year.

In Israel, meanwhile, talk of military action on Iran has crescendoed this month, although it is unclear whether it is real or bluff aimed merely at spurring US President Barack Obama into adopting a more hawkish position.

As a signatory to the nuclear non-proliferation treaty - unlike Israel, the Middle East’s only if undeclared state with the bomb - Iran’s nuclear facilities are under constant IAEA surveillance and are subject to frequent inspections.

A Western diplomat said Friday that the agency planned to form a “task force” including experts from several fields to pool its resources more efficiently on its investigation into Iran.

At Friday’s meeting, the IAEA wants Iran also to explain indications that at least until 2003, and possibly since, Tehran carried out “activities relevant to the development of a nuclear explosive device.”

So far Iran has flatly rejected the claims, set out in a major report last November, saying they are based on forged documentation provided by Western and Israeli intelligence.

The meeting comes ahead of the release, possibly next week, of the IAEA’s latest quarterly report on Iran which is expected to show that Tehran is continuing to expand its nuclear programme despite sanctions and talk of war.

Western diplomats told AFP they think the report will say that Iran had installed but not yet started operating possibly several hundred more centrifuges to enrich uranium to 20 percent purity at Fordo.

Enriched uranium is the main concern of the international community because it can be used not only in power generation and for medical isotopes but also, when purified to 90 percent, in the explosive core of a nuclear bomb.

The Fordo site is dug into a mountain near the holy city of Qom, making it difficult to bomb, and Iran has told the IAEA that it will eventually house 3,000 centrifuges. Around a third of these were in place as of May, the last IAEA report said.

Iran rejects Western accusations that it is seeking - or has ever sought - to develop atomic weapons and says that its nuclear programme is peaceful.

The IAEA wants access to specific documents and to scientists involved in Iran’s programme, as well as to sites, including the Parchin military base near Tehran, which it visited twice in 2005 but which it wants to look at again.

Iran has said it will allow access only as part of a wider arrangement governing relations between Iran and the watchdog that experts and diplomats say would limit to an unacceptable degree the IAEA’s inspection rights.

Western countries have accused Iran of bulldozing parts of Parchin to remove evidence, and the IAEA said in May that activities spotted there by satellite “could hamper the agency’s ability to undertake effective verification.”

The Western diplomat said they expected the IAEA to say in its report next week that Parchin has been altered so much that inspecting it now would be “irrelevant and academic.”

The talks began at around 10am (0800 GMT). It was unclear how long they would last.