The U.S. White House said on Monday that it was "unaware" of a letter from Iranian President Mahmoud Ahmadinejad to U.S. President George W. Bush.

"We are unaware of any such letter," said Fred Jones, the spokesman for the White House National Security Advisor.

The US State Department also said it had no details about the letter. "We are trying to ascertain the facts," State Department spokesman Sean McCormack said, adding "I only read news reports about it."

The United States, which severed diplomatic relations with Iran since 1980 after the seizure of US hostages in Tehran, has no official contact with the Islamic Republic.

Source: Xinhua