The meeting -- involving foreign ministers of the six world powers -- comes a day after talks between EU foreign policy envoy Javier Solana and Iran's top nuclear negotiator, which were described as "disappointing" by EU officials.

World powers are seeking a rapid response from Iran on a package of economic and political incentives designed to persuade it to freeze uranium enrichment -- a process needed to fuel a nuclear reactor but which could also be used to make a bomb.

The European Union, backed by the United States, Russia and China, made the offer to Iran on June 6, and Washington has repeatedly warned that Iran would be exposing itself to Security Council action if it rejects the offer.

Though pressed to give a response before a meeting of the Group of Eight major industrialised countries in Russia this weekend, Iran has repeatedly said it would not answer before August.

Following Tuesday's talks in Brussels, Iran's nuclear envoy Ari Larijani warned of a "long road" ahead in Tehran's standoff with the West.

He said the offer of incentives was "broadly suitable" but that the issue of suspending enrichment remained a central problem.

Iran insists that it only wants to develop nuclear energy although its lack of cooperation with the UN nuclear watchdog and enrichment activities have raised suspicions that it is covertly trying to build an atomic bomb.

In Tehran, Iranian President Mahmoud Ahmadinejad upped the rhetoric, warning that Iran would give no ground and vowing to continue sensitive nuclear fuel cycle work.

Washington immediately responded by saying the demand for suspension of Iran's enrichment activities was non-negotiable.

US State Department spokesman Sean McCormack said that a united position would be laid out at the Paris talks, adding that he had "detected no division" in the group about how to move forward.

Russia and China -- which have UN Security Council veto rights -- have both made it clear they oppose sanctions against Iran.

The Paris talks start at 1400 GMT at the French foreign ministry.

France's Foreign Minister Philippe Douste-Blazy will host his US counterpart Condoleezza Rice, Britain's Margaret Beckett, Russia's Sergei Lavrov, Germany's Frank-Walter Steinmeier and the Chinese deputy foreign minister Zhang Yesui, as well as Solana.

Douste-Blazy is to make a statement to the press after the end of the talks.