Updated

A third person separate from the two prisoners and documents previously disclosed provided information indicating Al Qaeda (search) was plotting to attack U.S. financial buildings, Bush administration officials said Wednesday in seeking to counter criticism their latest terror warning was overblown.

The White House described the information from the third person as "another new stream of intelligence" that supported its decision to issue the warning. It arrived days before the public alert, as officials were reviewing reams of recently obtained documents and photographs that showed surveillance of five buildings in New York, New Jersey and Washington carried out years earlier by Al Qaeda.

"Old information isn't irrelevant information — particularly with this kind of enemy," Homeland Security Secretary Tom Ridge (search) said Wednesday in Nashville, Tenn.

The information corroborating Al Qaeda's intentions to carry out attacks against U.S. financial buildings came from someone other than two recently captured suspects in Pakistan, said a senior Justice Department official, speaking on condition of anonymity. It was unclear whether the person was a prisoner or informant.

Information from those two suspects — a young militant familiar with computers and a man indicted for the U.S. embassy bombings in Africa in 1998 — had provided the bulk of the intelligence that led to Sunday's warnings.

The corroborating information did not specify targets in the United States or say when an attack might be planned, the official said. But it so closely tracked the other intelligence that U.S. financial buildings had already been under surveillance by Al Qaeda that it contributed to the decision to issue the public warnings.

"Coupled with general threat reporting, coupled with other pieces of information, then all of the sudden you say to yourself, 'This is a time when we have to talk to America about the threat.' And that's exactly what we did," Ridge said.

A U.S. counterterrorism official, also speaking on condition of anonymity, said the surveillance information last week was married with "very recent and current activity" from Al Qaeda, indicating the group's interest in attacking this year. This information, which includes debriefings and other means of gathering information, is causing the administration serious concern, the official said.

"A bunch of things came together at the same time," Frances Townsend, the White House Homeland Security adviser, said in an interview Wednesday with National Public Radio. She said the corroborating information came from "a very sensitive ongoing investigation in another part of the world."

The FBI is monitoring Al Qaeda operatives and others associated with Islamic terror groups inside the United States, although these people have not been directly linked to the threat against financial buildings, the Justice Department official said. These people include financiers for Ansar al-Islam, a group linked to Al Qaeda, the official said.

White House spokesman Scott McClellan (search) declined to describe in detail what he called "another new stream of intelligence," saying it might endanger continuing intelligence operations. He criticized as an "irresponsible suggestion" any criticism that the administration had issued a terror warning for political purposes.

"When you connect all these streams of intelligence, it paints an alarming picture," McClellan told reporters aboard Air Force One during a campaign flight to Iowa.

Ridge and other senior administration officials spent a second day Wednesday defending the warnings, which came on the heels of the Democratic National Convention and drew attention from the presidential campaign of nominee John Kerry.

"I categorically state that the none of the terror threats are politically motivated," Ridge said.

In New York, Treasury Secretary John Snow (search) said suggestions that terror alerts were manipulated were "pure, unadulterated nonsense." Snow toured the floor of the New York Stock Exchange and praised traders for their resilience in the face of such warnings.