by PAOLA TOTARO

Osama bin Laden is planning an attack against the United States that will "outdo by far" September 11, 2001, an Arab newspaper in London has reported.

And, a former senior Yemeni al-Qaeda operative said, the terrorist organisation has entered a "positive phase", reinforcing specific training camps around the world that will lead the next "wave of action" against the West.

The warning, on the front page of an Arabic newspaper published in London, Al-Quds Al-Arabi - and reported widely in the major Italian papers - quotes a person described as being "very close to al-Qaeda" in Yemen.

The paper is edited by Abdel al-Bari Atwan, who is said to have been the last journalist to interview bin Laden, in 1996.

Bin Laden is himself closely following preparations for an attack against the US and aims to "change the face of world politics and economics", the report says.

The former operative is quoted as saying that "this will be shown by the fact that we now control a major part of the south of Somalia".

He says he remains in contact with current chiefs of the organisation in Yemen and that, only six months ago, bin Laden sent a message to all jihad cells in the Arab world, asking them not to interact with their governments or local political parties and to deny any request for mediation or formal talks.

The source also said that, during the next few days, the terrorist organisation might send a sign of its violent intentions.

The warning has emerged at the same time as publication of a report leaked to London's Telegraph newspaper, which reveals that a document drawn up by the intelligence branch of the Ministry of Defence says that thousands of extremists are active in Britain.

The document says the operatives are predominantly British-born and aged between 18 and 30. Many are believed to have been trained in overseas terrorist camps.

Security officials are convinced al-Qaeda cells will attempt another "spectacular" inside Britain with major transport centres, such as airports and train stations, the most likely targets, the Telegraph reports.

Other targets include the Houses of Parliament, Whitehall and Buckingham and St James' palaces, with the threat level described as "severe".