The 2008 package was offered after world powers proposed economic incentives to help Iran's civilian nuclear programme in return for a halt to enrichment activities.

Uranium enrichment is a process which makes nuclear fuel as well as the core of an atom bomb, and the West fears Iran is secretly trying to build nuclear weapons, a charge persistently denied by Tehran.

Alireza Ronaghi, Al Jazeera's correspondent in Tehran, said: "Iran is trying to prove to the world that it has always been playing by the rules and that it is the world that has discredited itself, somehow."

Obama overtures

Saeed Jalili, Iran's senior nuclear negotiator, said on Monday that Tehran was ready to talk with the P5-plus-1 to resolve the long-running deadlock.

His remarks came after the six nations decided to invite Iran for talks, a result of several overtures from the administration of Barack Obama, the US president, towards Tehran.

The New York Times reported on Tuesday that US and European diplomats could scrap their demand that Iran cease enriching uranium at the start of talks with the six nations, which would mark a significant shift in policy.

But the report was dismissed by White House spokesman Robert Gibbs as not "accurate".