Probers Note Similarities With Madrid Attacks

The statement also predicted more attacks in Europe, singling out Denmark and Italy, both of which have sent troops to Iraq.

Two days after the bombings in Spain, a previously unknown group calling itself "al Qaeda in Europe" asserted responsibility for the attacks in a videotape that was found by investigators. In the videotape, a man who identified himself as the network's military spokesman said the bombings were "a response to the crimes that you have caused in the world, and specifically in Iraq and Afghanistan, and there will be more, if God wills it."

It is unclear if the two groups are related, or even if they played any role in either attack. Spanish investigators arrested dozens of suspects in the Madrid case, including several members of the Moroccan Islamic Combatant Group, a network of radicals affiliated with al Qaeda. But European counterterrorism officials have said they still don't know who gave the order for the Madrid attacks. Nor are they sure if they were conceived locally or directed from elsewhere.

Similarly, Moroccan officials remain unsure about who may have inspired the suicide attacks on Jewish and Western targets in Casablanca in May 2003 that killed 45 people, and Egyptian authorities have not concluded their investigation into bombings at several Red Sea resorts last October that killed 34 people.

Counterterrorism officials and analysts in Europe, North Africa and the United States have said that since the Sept. 11 hijackings, an increasing number of terrorist attacks have been planned and carried out by Islamic radicals who have fleeting, if any, ties with the central al Qaeda organization led by Osama bin Laden.

But according to the officials and analysts, the local groups may be sharing information or receiving direction from organizers with experience in arranging such plots.

"What we're seeing are far more autonomous groups that are inspired by al Qaeda's message of hatred of the West," said Alex Standish, editor of Jane's Intelligence Review and senior research fellow at Durham University in England.

"In the last few years, these groups seem to have adopted a very cellular structure. Most of them have very tightknit cells, with eight to 10 individuals or so, who have personal links that go back for years."

U.S. intelligence agencies began sifting through communications intercepts from the time of the blasts and were re-examining data collected in the past few weeks for clues to Thursday's attacks. Current and former intelligence sources said it was too early to make a definitive judgment but suggested there were "no indications that bin Laden's al Qaeda was behind this," according to one source.

"The good news is that it is difficult for bin Laden to issue orders and direction to people now," another intelligence official said on condition of anonymity. "But the bad news is that it is harder to track and stop inspired groups who leave fewer footprints, communicate less and don't need to travel as far."

U.S. intelligence officials did not dismiss the possibility that Abu Musab Zarqawi, a longtime Islamic radical who has helped direct the insurgency against U.S. forces in Iraq, could have inspired or directed the explosions in London.

Zarqawi's network has recruited fighters from across Europe and has been blamed for planning attacks in Germany and Britain.

CIA Director Porter Goss said in Senate testimony in February that Zarqawi's aim is to use Iraq as a base, as al-Qaeda had done in Afghanistan, and carry out attacks against Western targets outside the country.

Staff writers Dan Eggen and Susan B. Glasser in Washington, staff writer Dafna Linzer in New York and researcher Julie Tate in Washington contributed to this report.