Mohamed ElBaradei arrived in Tehran with an April 28 deadline for possible sanctions set by the UN approaching
Mohamed ElBaradei arrived in Tehran for new talks to resolve the stand-off over Iran's nuclear project today as the country pledged to advance to a new phase in uranium enrichment.

The head of the International Atomic Energy Agency (IAEA), the UN's atomic energy guardian, said that he remained hopeful Iran could still be persuaded to suspend its research through diplomacy.

His optimism met an early setback this morning, when the President Mahmoud Ahmadinejad pledged that Iran would not "retreat".

A senior Iranian official confirmed that the Islamic republic now intended to expand its programme to manufacture a cascade of 54,000 centrifuges capable of high-grade, industrial-scale enrichment to produce fuel for power stations. The West fears that the research is a front for a weapons programme.

Today's talks will be conducted against a backdrop of escalating rhetoric between Iran and the West as the April 28 deadline for possible sanctions set by the United Nations Security Council approaches.

In what many are viewing as a carefully timed piece of political theatre, Mr Ahmadinejad responded to media suggestions that the US was preparing for a military strike against Iran by announcing on Tuesday that his scientists had made a breakthrough in their research.