In London, Islamic Radicals Found a Haven

But Qatada is better known as an ideologue of global holy war than an organizer of it. When Sept. 11 hijacker Mohamed Atta's apartment in Germany was searched, authorities turned up videotapes of Qatada's London sermons. The British arrested Qatada in late 2002 but he was never charged and was released in March. "He's been cited as the spiritual leader by at least a half dozen terrorist cells," said Evan F. Kohlmann, a researcher who has written a book on Islamic terrorist groups in Europe.

For al Qaeda and its affiliates, the British capital has been considered an indispensable communications center. "They looked on London as the premier place for propaganda in the Western world," said Michael Scheuer, who headed the CIA's special bin Laden unit in the mid-1990s.

Even after the arrest of al Qaeda's London spokesman, Fawwaz, London remained a clearinghouse for the group's information and ideas. Just a few months after Sept. 11, bin Laden's chief deputy, Egyptian doctor Ayman Zawahiri, published from hiding a lengthy memoir-cum-holy war-treatise, "Knights Under the Prophet's Banner," as a 12-part series in the London newspaper Al-Sharq al-Awsat.

The shock of Sept. 11 brought a sharp increase in British arrests of Islamic militants, many with some alleged connection to al Qaeda. But clerics like Qatada who worked in what Simon, the former counterterrorism official, called "the realm of inspiration" have continued to preach holy war in London. Altogether, 700 suspects were taken into British custody under the counterterrorism law between 2001 and the end of 2004. Only 17 have been convicted.

Among those arrested after 2001 was Yasir Tawfiq Sirri. A slight, balding man who ran a group called the Islamic Observation Center, he was mostly known up to that point for press releases critical of the Egyptian government. Simon recalled meeting Sirri in a London hotel lobby and thinking of him as "an allegedly retired Egyptian militant." Later in 2001, the men who killed the Afghan anti-Taliban leader Massoud, gained entry to his compound by claiming to be Arab journalists from Sirri's London group. Sirri was arrested in London after the Sept. 11 attacks but was never prosecuted.

British citizen Ahmed Omar Saeed Sheikh was arrested in 2002 in connection with the murder of Pearl, the journalist, in Pakistan. Radicalized while attending the London School of Economics, he had hoped to fight in Bosnia in the 1990s but ended up instead with a Kashmiri militant group. He was charged with organizing Pearl's kidnapping, but al Qaeda's operational chief, Khalid Sheikh Mohammed, allegedly killed the American journalist.

British-born Saajid Badat was another worshiper at Masri's Finsbury Park mosque who went through the Afghan camps. Badat was a would-be shoe bomber, who meant to blow himself up at the same time as Reid; he testified that he changed his mind and dismantled his bomb. Convicted earlier this year, Badat reportedly received orders from Khalid Sheikh Mohammed.

British authorities have broken up what they claimed were several different cells with al Qaeda connections. One group, arrested in 2004, was accused of storing a half-ton of ammonium nitrate, which can be used in explosives, in a locker near Heathrow Airport. Another group was arrested in 2003 and charged with plans to use the deadly poison ricin in an attack -- although only one man was convicted, not for manufacturing ricin but for killing a British officer who came to arrest him.

A raid on an al Qaeda computer expert in Pakistan in 2004 led to arrests of nearly a dozen men in Britain, including a Muslim convert of Indian origin, who were accused of casing financial targets in Britain and the U.S. in preparation for an attack.

The portrait of those arrested suggests the diverse mosaic of Islamic extremists making London their home today, with few of those taken into custody by the British since Sept. 11 conforming to the original al Qaeda profile of Saudis and Egyptians. Instead, a review by The Washington Post of nearly 62 cases of men arrested here found the largest group -- 31 -- to be from North Africa, followed by 12 British citizens and seven Pakistanis. Many were educated in British institutions and were middle class, though some, such as radical clerics Masri and Qatada, collected welfare benefits.

An 'Inevitable' Attack

Until last week, whether London was a target of al Qaeda had been a source of debate.

Some experts, like Scheuer, believed that bin Laden had long wanted to hit the city, ever since the arrest of his aide, Fawwaz. Bin Laden blamed the arrest publicly on "British Crusader hatred of Muslims" from his refuge at the time in the southern Afghan city of Kandahar.

Other analysts, such as Simon, believed that, up until 2001, "Britain was regarded as too valuable a staging area" for al Qaeda to attack.

But ever since, it has been a key target.

One of London's radical Islamic clerics, Syrian-born, Saudi exile Omar Bakri Mohammed, openly spoke of the time when the city that gave him refuge back in 1986 would be hit. "It's inevitable," Mohammed, well known for attempting a public celebration in honor of the Sept. 11 hijackers, told a Portuguese magazine last year. Among the groups mobilizing for a strike was one calling itself al Qaeda in Europe. It "has a great appeal for young Muslims," he said. "I know that they are ready to launch a big operation."

In Finsbury Park, a ragged and lively neighborhood of new immigrants, a moderate faction has now taken control of the red-brick mosque where Masri once delivered his fire-breathing sermons. As worshipers arrived for prayers on Friday, they passed beneath a banner advertising "A New Beginning for the Mosque" and a "Better Community Image."

Mohammed Nusa, 18, loitered outside, talking about the bombings and the backlash against Muslims he now feared. That backlash, in turn, may help the Islamic radicals, Nusa said. He adamantly rejected Masri's ideology but explained there are always a few among his friends who argue that "if they're going to make us look like the enemy, we might as well be the enemy."

Glasser reported from Washington. Staff researcher Julie Tate in Washington contributed to this report.