Terror cells 'no longer need approval' for fresh attacks

Osama bin Laden has delegated the authority to order new terrorist strikes to individual cells within his al-Qa'ida network, American intelligence officials believe.

Mr bin Laden is thought to have told al-Qa'ida operatives they can launch new operations without prior approval. The order is believed to have been the main reason for Monday's formal warning by the American government of possible attacks in the next week.

This means that even if the Allied military campaign, which is in its fourth week, is successful in killing Mr bin Laden and his senior lieutenants, further attacks may not be prevented, a horrifying reality for efforts to counter the threat of terror attacks inside America and on US targets overseas.

Up to half a dozen cells operating in America have been identified since the 11 September attacks, though the authorities are not sure they have arrested all their members.

The warning on Monday night, said to be based on "credible" information, was issued to America's 18,000 law enforcement agencies. They were put on the highest state of alert. While the alert was not specific about the location of possible attacks, they may be linked with the American Midwest, The Independent has learnt.

Law enforcement agencies in Wisconsin were told to prepare. A source informed of the announcement said: "The warning said to expect something in the Midwest. It was specifically about the Midwest."

The latest alert is believed to be based on information from human sources and satellite intelligence. Officials said it came from a source that had proved reliable in the past, and that the details received stood out from the usual stream of information received every day.

Tom Ridge, America's homeland defence director, said: "When we do have, from credible sources, a strong suggestion that this is a week that we may see additional terrorist activity in this country ... we need to heighten awareness."

Another official said the intelligence referred to conversations that used language similar to that intercepted by intelligence agents before 11 September. The official said there had been an increase in the number of references and the force of the language used.

Mr bin Laden's decision to delegate decision-making to individual cells was said to be among the most worrying information. The Washington Post said intelligence analysts had concluded that al-Qa'ida cells no longer needed approval for operations from the network's senior figures.

On the military front, American soldiers were confirmed to have established a land base inside Afghanistan to co-ordinate attacks with the Northern Alliance opposition. A spokesman for the group, Mohammed Ashraf Nadeem, said that 15 to 20 uniformed American soldiers were at a base in the Northern Alliance-controlled village of Dar-e-Suf.

Donald Rumsfeld, the Defence Secretary, said from the Pentagon: "We do have a very modest number of ground troops in the country and they are there for liaison purposes."

In another important development, news emerged that Saudi Arabia may end its ban on America using a state-of-the-art military facility at Prince Sultan base, after talks between King Fahd and US General Tommy Franks, the commander of Operation Enduring Freedom.