The arrest of Al Qaeda leader Khalid Shaikh Mohammed and financier Mustafa Ahmed al-Hawsawi has led to a fount of information about major Al Qaeda operatives and contributors, including those in the United States, senior U.S. officials said Thursday.

Satellite phone and computer data from Mohammed are providing new ways to track Al Qaeda operatives, and al-Hawsawi's computer disks include lists of contributors around the globe, including bank account numbers and names of organizations that have helped finance terror operations.

That may help the CIA and FBI arrest more terrorists and bust up terror cells. A government official confirmed Thursday that the information has yielded the identities of about a dozen suspected terrorists in this country.

However, the FBI warned law enforcement agencies throughout the country Wednesday that the apprehension of Mohammed could accelerate attacks against the United States already in the planning stage.

The bureau confirmed in the weekly bulletin it sends to 18,000 state and local law enforcement units that Mohammed and al-Hawsawi, a Sept. 11 financier, are in U.S. custody and have been transferred to a secure site outside Pakistan where they are being interrogated.

The FBI bulletin says that Mohammed's capture "deals a severe long-term blow" to Al Qaeda's ability to carry out attacks.

"However, in the short term, the apprehension may accelerate execution of any operational planning already under way, as operatives seek to carry out attacks before the information obtained through Mohammed's capture can be used to undermine operational security," the bulletin reads. The bulletin doesn't contain a specific threat.

Mohammed, Al Qaeda's No. 3 official, whom an Al Jazeera reporter said admitted to having planned the Sept. 11 attacks in New York and Washington, is also wanted for the bombing of a synagogue in Tunisia, the planned bombing of airplanes over the Pacific Ocean and other attacks. The FBI bulletin said that in 2002 Mohammed met with Jose Padilla, a U.S. citizen now in federal custody on charges that he planned to detonate a radiological "dirty bomb" in the United States.

While the Bush administration has been widely commended for the capture, one law enforcement official told Fox News the announcement about the arrest of Mohammed came sooner than some desired.

The publicity came before the CIA and the FBI had a chance to follow up on information gathered during his arrest and after, the source said. Some law enforcement officials are worried that the premature publicity alerted Mohammed's cohorts and may have pushed them underground.

Some investigators are now questioning whether other Al Qaeda members, including key figures, have had the time they needed to scramble.

One analyst with good sources on Al Qaeda's activities in the region suggests that the apprehension of Mohammed could be putting pressure on Usama bin Laden to leave the region.

The interception of some letters in recent weeks believed to be written by bin Laden indicate that he is preparing to leave his hiding place, perhaps in eastern Pakistan. Fox News foreign affairs analyst Mansoor Ijaz said the capture of Mohammed adds to U.S. and Pakistani pressure on tribal leaders to stop aiding the FBI's most wanted fugitive.

"He had no choice [but to prepare an escape], because a) he was running out of money essentially to bribe them with and keep the safe harbor intact, and b) he was getting from a lot of tribal chieftains that it was time to go, and they could not hold the system up that could protect him any longer," Ijaz said.

In letters believed to be seized in the Rawalpindi raid that captured Mohammed this weekend, bin Laden appears to be sending goodbye message to his inner circle. Rawalpindi and other urban centers along the Indus River, including Lahore and Karachi, have been considered good hiding places because they provide easy access to ocean-going vessels. Ijaz said senior Al Qaeda members prefer to travel by sea because it is much harder to detect their movements.

The letters could be proof that bin Laden survived the punishing assault on Tora Bora, Afghanistan, in 2001 and continues to play an active role in the network. However, a U.S. official was cautious, saying that he has not seen such letters and neither confirmed nor denied their existence.

Dead or alive, Sen. Pat Roberts, R-Kan., chairman of the Senate Intelligence Committee, said next to grabbing bin Laden, the capture of Khalid Shaikh Mohammed represents a "real damaging blow to Al Qaeda. In terms of future attacks, there's nobody that we think in Al Qaeda that has the kind of comprehensive background to operate as 'the brain' behind any [terrorist] operation."

Fox News' Catherine Herridge, Molly Henneberg and Anna Stolley and The Associated Press contributed to this report.