Al-Jazeera television in Qatar tonight broadcast an audio tape from Osama bin Laden calling on Muslims to support Iraq.
US Secretary of State Colin Powell said earlier today that the US was aware of the tape. Tonight, a senior official said the United States believed the tape was genuine.
A State Department spokesman noted that the voice on the tape threatened not only the US but also half-a-dozen Arab nations, excluding Iraq.
Washington has regularly accused Al-Jazeera of being a mouthpiece for the al Qaeda leader.
Mr Powell sought to make the Iraq/al Qaeda connection in a 5 February address to the UN Security Council, but Iraq has vehemently denied it. The US claim has met with international scepticism.
A US official said US intelligence sources were not yet aware if the tape contained any specific new anti-US threats.
CIA boss warns of possible terrorist attacks
Earlier today the CIA Director, George Tenet, warned of possible terrorist attacks in Saudi Arabia and the United States as early as the end of the Hajj Muslim pilgrimage late this week. He said the attacks could include the use of radiological devices, poisons and chemicals.
Mr Tenet said that the information they had received was the most specific they had seen and was consistent with both their knowledge of al Qaeda doctrine and the network's strategies.
George Tenet also told the US senate intelligence committee that the al Qaeda network had established a presence in Iraq and Iran.
In his congressional testimony, Mr Tenet claimed Iraq was harbouring senior members of the terrorist network led by Abu Musab al-Zarqawi, a close associate of Osama bin Laden.
Meanwhile FBI Director, Robert Mueller, has said that unidentified al Qaeda groups on US soil constitute the single largest threat against the United States.
Troops deployed over Heathrow terrorist fear
Troops have been deployed at London's Heathrow airport amid fears of a new terrorist threat from al Qaeda.
More than 400 troops have been drafted in at the airport and at a number of other unspecified sites in London.
Scotland Yard said the precautions were being taken to coincide with the Muslim festival of Eid al-Adha.
Troops with armoured vehicles and army trucks took up their positions at Heathrow early this morning. Police levels at the airport have also been tripled.
The intelligence services in Britain fear that al Qaeda could use the end of the Eid festival - which runs until Saturday - to launch attacks in London and specifically at Heathrow.
The British government says it is taking necessary action to protect the public. At least one London-based Muslim group has dismissed the move as Islamophobic and provocative.
The last time troops were deployed at Heathrow in such numbers was in 1994 following an IRA mortar attack on an airport runway.
Visible security at Heathrow is likely to remain extremely high for several days.
