The U.S. Secretary of State Condoleezza Rice said on Wednesday that Iran's letter, sent to President George W. Bush by his Iranian counterpart Mahmoud Ahmadinejad, was "not a serious diplomatic overture."

"That is not a serious diplomatic overture," Rice told NBC television, noting that there was "nothing in it that suggested a way out of the nuclear stalemate."

Rice said on Monday that the letter, which was the first from an Iranian leader to a U.S. president in 27 years, contained no proposals for resolving the confrontation over Iran's nuclear ambitions.

"This letter is not the place that one would find an opening to engage on the nuclear issue or anything of the sort. It isn't addressing the issues that we're dealing with in a concrete way.... It is most assuredly not a proposal," Rice said.

Iran's President Mahmoud Ahmadinejad wrote a letter to U.S. President George W. Bush on finding new solutions to their differences, the Iranian government spokesman Gholam Hossein Elham said on Monday.

The letter was delivered to U.S. President George W. Bush by the Swiss Embassy to Iran, Elham said.