Iran has shot itself in the foot by failing to engage with the UN atomic agency, lowering the chances of renewed six-party talks and stoking speculation of military action, analysts said Wednesday.

Moreover, the failure of the International Atomic Energy Agency's visit to Iran could help overcome Russian and Chinese resistance to increasing the heat on the Islamic republic, experts believe.

"Diplomacy with Iran would be meaningful only if Iran would bring to the table evidence that it was cooperating with the IAEA," Mark Hibbs, analyst at the Carnegie Endowment for International Peace, told AFP.

"That hasn't happened after two IAEA visits to Iran," he said.

The IAEA said in the early hours of Wednesday that its latest visit to Tehran, its second in less than a month, had failed to produce a breakthrough in clarifying suspicions that Iran has done work developing nuclear weapons.

"It was clear that Iran had to offer something concrete and to accommodate IAEA requests for access to sites and personnel," said Shannon Kile at the Stockholm International Peace Research Institute (SIPRI).

The fact that they didn't was not "unexpected," however, he told AFP.

Despite Iranian denials, most recently on Wednesday from supreme leader Ayatollah Ali Khamenei, Western countries and Israel -- which Tehran says it wants to wipe off the map -- strongly suspect that Tehran wants the bomb.

A watershed IAEA report in November accusing Tehran of a whole host of activities heightened these suspicions, leading to tighter US and EU sanctions and speculation Israel could bomb Iran, possibly as early as April.

Despite this, and sanctions clearly biting, Iran has continued to play hardball, talking up progress in its nuclear programe, threatening a cut in oil sales to Europe and conducting ostentatious displays of its military might.

At the same time, meanwhile, Iran last week signalled its readiness to return to talks with the the P5+1 powers -- the United States, China, Russia, France, Britain and Germany -- which broke down in Turkey 13 months ago.

The glaring absence of Iranian willingness to engage with the IAEA though puts paid to hopes these negotiations will resume, said Oliver Thraenert from the German Institute for International and Security Affairs (SWP) in Berlin.

"This shows clearly that Iran is not in the mood for substantial compromise. The chances now of a return to negotiations between Iran and the P5+1 are not very high. It leaves matters in a deadlock," he told AFP.

US President Barack Obama "would want talks to result in something concrete, he is not interested in just talks for talks, as was the case in Istanbul," Thraenert added.

Iran's behaviour, including what IAEA chief Yukiya Amano called its "disappointing" refusal to allow inspectors access to the Parchin military site, will also go down badly in Moscow and Beijing, experts believe.

"The Chinese in particular have made it clear that they do not want to see Iran becoming nuclear, and they have no interest in games such as Iran closing the Strait of Hormuz," Thraenert said.

A change in Russian and Chinese attitudes -- hitherto easier than the West on Iran -- could be in evidence as early as March 5 when the IAEA's 35-nation board chews over the situation, Hibbs said.

"China and Russia so far have refused to join the West in adding to sanctions. If Amano tells the (IAEA) governors Iran isn't cooperating, China and Russia will be under pressure to take a more active role in finding a diplomatic solution to the crisis," Hibbs said.

"Russia and China will definitely see this as a setback, but it is not clear that this will necessarily get them on side for more sanctions" in the Security Council, cautioned however SIPRI's Kile.