The United States will hunt down and punish those responsible

President Bush

"We will do what it takes. No one is going to diminish the spirit of this country," he added.

Mr Fleischer said the president's address is likely to be "a message of resolve ... a reassuring message that our nation has been tested before, our nation has always prevailed."

In the immediate aftermath of the attacks, Mr Bush told reporters: "Freedom itself was attacked this morning by a faceless coward ... and freedom will be defended."

"The United States will hunt down and punish those responsible for these cowardly acts".

"All appropriate security precautions have been taken to protect the American people" he said in the wake of Tuesday's attacks in New York and Washington.

The president was speaking at Barksdale Air Force base in Louisiana while on his way to Nebraska.

Nebraska

He learnt of the attacks in Florida, where he had been on a two-day visit.

President Bush heard the news at a Florida primary school

He was flown in Airforce One to Offutt airbase in Nebraska, the strategic air command headquarters in the case of war.

"The resolve of our great nation is being tested," he said in a short stopover in Louisiana. "We will show the world that we will pass the test."

President Bush left Sarasota in Florida less than an hour after the first reports of the attacks. He had been due to speak at a primary school when he heard news of the Trade Center explosions in New York.

Speaking briefly after the first two explosions had been reported, Mr Bush said it was "a national tragedy", and a "difficult moment for America."

Visibly shocked by the reports, the president said he had been in touch with the vice-president, the governor of New York and the director of the FBI to order a full investigation.

"The full resources of the government to go to help the victims and their families and to conduct a full-scale investigation to hunt down and to find those folks that committed this act," he said in Florida.

President Bush added: "Terrorism of this kind will not stand."

He left the school after calling for a moment's silence and for prayers for the victims and their families, and headed for the airport.

Vice-president

While President Bush is out of Washington, Vice-President Dick Cheney has been monitoring the situation from a secure location within the White House.

US Secretary of State Colin Powell, who was attending a meeting of the Organization of American States in Lima, the capital of Peru, immediately flew back to the United States.

He said attacks of this kind "will never kill the spirit of the American people."