Iranian President Mahmoud Ahmadinejad (file photo)

Iran's President Mahmoud Ahmadinejad has voiced defiance, as a U.N. deadline approaches for Iran to stop its sensitive nuclear activities.

Mr. Ahmadinejad said in Tehran Tuesday no one can prevent Iran from having a peaceful nuclear program. He also said it is unlikely the U.N. Security Council will act against Iran.

Iran faces a U.N. Security Council deadline Thursday to stop uranium enrichment, or face possible sanctions.

In Washington, U.S. State Department spokesman Tom Casey says he fully expects sanctions if Iran fails to meet the deadline. He refused to give a specific date when the sanctions would take effect.

The West accuses Iran of trying to develop nuclear weapons. Iran says its nuclear program is only to generate electricity.

During his news conference, Mr. Ahmadinejad proposed holding a live television debate with President Bush on global affairs. The White House called the proposal an attempt to divert attention from Iran's nuclear activities.

The Iranian president also said the U.S. has been "dreaming about turning Iran back 30 years."

Nearly three months ago, the U.S. and other world powers (the other permanent members of the Security Council, plus Germany) offered Iran a package of incentives if it ends sensitive nuclear work and returns to negotiations on its standoff with the West.