"We have a preference for diplomatic solutions," a source at the Spanish foreign ministry said when asked about Spain's position on Kouchner's proposal.

He said Spain backs the diplomatic efforts led by the International Atomic Energy Agency (IAEA), by European Union foreign policy chief Javier Solana and by the six members of the UN Security Council -- the United States, France, Britain, Germany, Russia and China.

"We believe it's necessary to use the deadlines, in particular those set by the IAEA, to achieve progress."

Spain believes Iran "must make gestures" but "we think that the framework for a solution, including sanctions, should be global, in this case the UN," the source said.

In a letter released Wednesday, Kouchner urged his EU partners to impose new economic sanctions to pressure Iran to end its "nuclear defiance".

Britain said Thursday it "wholeheartedly" backs Kouchner's call.

Iran vehemently rejects charges by Western nations it is seeking a nuclear weapon, saying its nuclear programme is aimed solely at generating electricity for a growing population.

World powers have agreed to wait for reports due in November from the IAEA and Solana before deciding whether to submit a new sanctions resolution to the Security Council.