Hopes are riding high that mooted talks between Iran and world powers will de-escalate a dangerous showdown over Tehran's controversial nuclear programme.

While Iran and the so-called P5+1 comprising the five UN Security Council permanent members plus Germany, are expected to soon agree a date and place for reviving their long-stalled talks, the spectre of military confrontation looms large.

Israel has kept up warnings of air strikes on Iranian nuclear facilities to prevent the Islamic republic obtaining a nuclear weapons capability.

A majority of Israel's 14-member security cabinet now supports Prime Minister Benjamin Netanyahu and Defence Minister Ehud Barak in launching a pre-emptive attack on Iran in a bid to end its nuclear programme, the Israeli newspaper Maariv reported on Thursday, citing political sources it did not identify.

"Israel is very close to the point when a very tough decision should be made -- the bomb or the bombing," former military intelligence chief Amos Yadlin told reporters last week.

The United States, meanwhile, is positioning three of its aircraft carriers near Iran, according to the US navy on its official website.

The USS Enterprise a week ago left its home port to join the USS Abraham Lincoln and USS Carl Vinson that are already in the region. The Lincoln in January sailed through the strategic Strait of Hormuz into the Gulf, testing Iranian threats against the Vinson in that body of water.

The US navy is also doubling the number of minesweeping ships and helicopters based in the Gulf, according to testimony by its chief, Admiral Jonathan Greenert, to US senators.

US President Barack Obama has warned that Iran's leaders have to understand that "the window for solving this issue diplomatically is shrinking."

Iran maintains its nuclear programme is purely peaceful even though this year it blocked UN inspectors from visiting a specific area of a military base suspected to have hosted nuclear warhead research.

Tehran on Wednesday made a formal request to schedule the time and place for "constructive, serious" talks with the P5+1, which it agreed to on February 14 after an initial offer made back in October by EU foreign policy chief Catherine Ashton.

The last round of negotiations with the P5+1 collapsed in Istanbul in January 2011.

Iran's supreme leader Ayatollah Ali Khamenei, though, has told the West to drop the "illusion" that its economic sanctions against his country will force a change of heart over nuclear policy.

Khamenei has called nuclear weapons a "sin". Iran has stressed that it seeks only civilian uses from splitting the atom, such as nuclear energy and medical isotopes.

The Western sanctions are taking a toll on Iran's vital oil exports, though one that is quantifiably unclear overall amid competing declarations from Tehran and from Western agencies.

While shipments have certainly been curtailed to several markets, the tensions over the showdown have driven global oil prices higher, giving the Islamic state higher revenue per barrel of oil it manages to sell.

The International Atomic Energy Agency last November issued a report detailing suspicions that Iran was researching military aspects of nuclear technology, though it stopped short of stating definite proof of atomic bomb-related activities existed.

US intelligence has likewise said there was no evidence of an Iranian nuclear bomb and it was thought no decision had yet been made on whether to make one.