Bushehr - AP - Aug. 21, 2010
The reactor building of the Bushehr nuclear power plant is seen, just outside the southern city of Bushehr, Iran. Photo by AP

Iran's failure to engage in "serious" international talks on its nuclear programme "is frankly ridiculous," a senior European Union official complained on Tuesday, as the bloc
was waiting for Tehran's response on its latest offer of dialogue.

The EU's foreign policy chief, Catherine Ashton, has proposed that talks between Iran and the 5+1 group - comprising the United States, Britain, China, France, Russia and Germany - resume November 15-17 in Vienna.

"It is now more than a year since there was any serious conversation with the Iranians, and that is frankly ridiculous and leads to a good deal of frustration on our part," the EU source pointed out.

"I know this is shared by the Russians and the Chinese," the official added.

Earlier on Tuesday, Iranian Foreign Ministry spokesman Ramin Mehmanparast had said that no decision had yet been taken on attending the talks proposed by Ashton.

"Evaluations are still going on as not only the date and venue but also the agenda should be clarified," Mehmamparast said.

"We want the agenda to have content and not just form," Mehmanparast added.

The EU source said Iran should reply "at least a couple of weeks in advance" before the proposed date, as "anything less begins to look not very serious."

He also urged Iranian officials to use diplomatic channels rather than the media to express their willingness to talk.

Iranian Foreign Minister Manouchehr Mottaki later Tuesday rejected the remarks by the EU source and said negotiations are underway with the bloc to finalize a date and venue, as well as clarify the agenda.

"Both sides have expressed their political willingness to hold the negotiations and we hope that through talks which are underway, an understanding will also be reached on the agenda, besides date and venue," Mottaki told the official news agency IRNA.

The 5+1 group wants talks to focus on the nuclear dispute and Iran's refusal to suspend uranium enrichment while Tehran wants to discuss global issues.

"Pressures and ultimatums will not have any impact whatsoever on Iran's firm willingness to follow its rights on pursuing a peaceful nuclear programme,"Mehmanparast noted.

Iran's critics, however, worry it is using its nuclear programme to develop weapons.

The Iranian spokesman also condemned additional sanctions in the energy and financial sectors that EU foreign ministers approved in their final legal form on Monday, after having endorsed them politically in July.

"Contrary to what the EU claims, they just want to put pressure on the Iranian people and deprive them from their rights," Mehmanparast said.

"But they should know that such decisions will have no impact whatsoever on the will of the people and they will not surrender to such pressures," he said.

The full list of EU sanctions - adding to the measures agreed by the United Nations in June - is due to be published on the EU official gazette on Wednesday, officials from the bloc indicated.