"Once we have this all wrapped up in terms of some final details, then we'll be happy to talk about it more. Until that point, I will say that we are not going to be going to Tehran," State Department spokesman Sean McCormack said.

"We have laid out our conditions... for having discussions with the Iranians," he said, referring to the demand that Iran halt of all its enrichment and processing of uranium.

The six powers involved in the nuclear talks -- the United States, Russia, China, Britain, France and Germany -- decided May 2 in London to present a new offer to the Iranian government.

The six did not say how and when they would present the package to Tehran but diplomatic sources said negotiations are underway with Iran to send foreign ministry political directors from the six countries to Tehran.

They said the United States would not join the group led by European Union foreign policy chief Javier Solana who would probably leave next week.

Asked about the rumors, the State Department's acting political director, Daniel Fried, did not rule out that such a delegation would travel to Tehran, but said he would not be part of it.

"No way will I go with them. Never was in the cards," Fried told AFP.

© 2008 Agence France-Presse