World powers have agreed to a new round of talks with Iran just hours after the Israeli Prime Minister, Benjamin Netanyahu, appeared to signal that a new war in the Middle East was inevitable.
He warned that time was running out to stop Tehran from acquiring nuclear weapons.
The EU's foreign policy chief, Catherine Ashton, said yesterday that she had accepted an invitation from Saeed Jalili, Iran's chief negotiator, to talks on behalf of six world powers at a date and venue to be decided. Iran has also agreed to allow UN inspectors to visit a suspected nuclear weapons testing site known as Parchin.
The news came as David Cameron claimed that Iran wanted to build an "intercontinental nuclear weapon," as he warned Tehran that it needed to adopt a "big change" in its strategic thinking to avert conflict. After being briefed for an hour by the UK's national security adviser, he said of the option of using military action: "Nothing is off the table."
The renewal of negotiations over Iran's nuclear programme marks the first substantive contacts with the West since talks collapsed more than a year ago, and offer a glimmer of hope that intensifying international pressure on Iran is having an effect.
It could also afford Washington some leverage to restrain Israel from launching a pre-emptive strike on Iran's nuclear sites, a prospect that appeared increasingly likely this week after Mr Netanyahu raised the threat of a second Holocaust at the hands of a nuclear Iran.
Baroness Ashton, representing Britain, the United States, France, Germany, China and Russia, said she hoped that Iran "will now enter into a sustained process of constructive dialogue which will deliver real progress in resolving the international community's long-standing concerns on its nuclear programme".
William Hague, the Foreign Secretary, welcomed the development, but warned that the West would not ease the international pressure on Iran until it proved that its nuclear programme is "exclusively peaceful". Iran has long maintained that its nuclear research is for civilian, not military, purposes.
During a tense meeting in the White House this week, President Barack Obama again attempted to dissuade Israel's hawkish premier from a premature strike on Iran, asking that he allow time for sanctions to work.
But although Israel has not yet made the decision on whether to strike, Mr Netanyahu made it clear in an address to the American Israel Public Affairs Committee, the powerful pro-Israel lobby group, that its patience was running thin.