A White House official has warned that time is running out for Iran to work with the international community.

Jay Carney, press secretary for the Obama administration, said that “the window was closing” for the Ahmadinejad regime to cooperate over its nuclear ambitions.

“There is international consensus about the absolute need for the Iranians to abide by their obligations, to forsake their nuclear weapons ambitions, to demonstrate verifiably that they can reassure the world that they do not seek to acquire nuclear weapons.”

He said that “our bottom line, our position is that Iran must live up to its international obligations including the full suspension of uranium enrichment, as required by multiple UN Security Council resolutions.”

Mr Carney’s comments came ahead of scheduled talks between international negotiators and Iranian officials.

Speaking on Wednesday, Saeed Jalili, head of Iran's Supreme National Security Council and the chief nuclear negotiator, suggested the Islamic Republic could modify its stance at the meeting.

Mr Jalili told Press TV, Iran’s news channel, that representatives of the country planned to “participate in the negotiations with new initiatives”.

“We hope that the P5+1 countries will also enter talks with constructive approaches.”

Mr Carney also told reporters that the international community was united, while Iran was “isolated”.

He said: “The way to change that dynamic is for Iran to live up to its international obligations and to forsake its nuclear weapons ambitions.

"But there is enough time and enough space at this moment to pursue a diplomatic solution - that’s why the resumption of these talks is important.”