Airliner Plot Had Support In Pakistan, Officials Say

Two intelligence sources suggested that Pakistan had replaced Afghanistan as a center for terrorist activities and expressed frustration with the attempts of Pakistan's president, Gen. Pervez Musharraf, to exert control over huge swaths of territory.

The senior administration official did not play down the problem but insisted that the situation is better today than it was five years ago. "Prior to 9/11, the whole region was a safe haven," the official said. "You see attempts from Pakistan to affect this, but it's still part of a long-term element of our battle against terrorism." Pakistani officials say the country's efforts are sincere and pursued at major cost in lives and money.

In the days before the alleged airliner bombing plot was exposed, more than 200 FBI agents followed up leads inside the United States looking for potential connections to British and Pakistani suspects. The investigation was so large, officials said, that it brought a significant surge in warrants for searches and surveillance from the Foreign Intelligence Surveillance Court, the secret panel that oversees most clandestine surveillance.

One official estimated that scores of secret U.S. warrants were dedicated solely to the London plot. The government usually averages a few dozen a week for all counterintelligence investigations, according to federal statistics.

The purpose of the recent warrants included monitoring telephone calls that some of the London suspects made to the United States, two sources said.

At the Justice Department, prosecutors have debated and identified possible criminal charges that could be filed against those arrested, because they were targeting U.S.-bound flights. One official said they would defer to British prosecutors in the case, but wanted backup options in case their London counterparts encountered problems.

U.S. authorities were still unsure about how the plot may have tied into al-Qaeda.

Homeland Security Secretary Michael Chertoff said Friday that the case bore the "hallmarks of an al Qaeda-type plot," because of its similarity to an abortive 1990s plan directed by Khalid Sheik Mohammed, a senior al-Qaeda operative now in U.S. custody, to blow up a dozen airliners over the Pacific Ocean.

"We do not have evidence that there was, as part of this plot, any plan to initiate activity inside the United States or that the plotting was done in the United States," Chertoff told reporters at Reagan National Airport.

Researcher Julie Tate and staff writers Dan Eggen and Spencer S. Hsu contributed to this report.