Over the past six weeks, European investigators in four countries have arrested more than 50 people with suspected links to Osama bin Laden's Al Qaeda network. Police have uncovered explosives, chemicals, fake passports, and documents, including maps of the London Underground.

Algerians are consistently among those detained - a fact that Western intelligence officials say points to the formation of a North African network of Al Qaeda that is preparing to act.

Spanish Prime Minister José Maria Aznar, referring to the arrests Friday of 15 Algerians and a Moroccan in northeastern Spain, said police had broken up a "major terrorist network" linked to the Algerian Salafist group, a splinter of the Armed Islamic Group (GIA), which he said had clear links with Al Qaeda. He said the network also had connections with suspects recently arrested in France and Britain.