Days after raising the terror alert, officials at the Department of Homeland Security are on the defence over reports that their intelligence was three or four years old.

U.S. Homeland Security Secretary Tom Ridge admitted the information dated back to 2000 and 2001, but he said it was updated "as recently as January of this year."

"I don't want anyone to disabuse themselves of the seriousness of this information simply because there are some reports that much of it is dated, it might be two or three years old," Ridge said.

"This is the most significant, detailed pieces of information about any particular region that we have come across in a long, long time, perhaps ever," he said.

The terror alert came a week after Democrats nominated John Kerry as their presidential candidate, who is now neck-and-neck with Bush in the polls.

Ridge denied that the timing of the terror alert was politically motivated. He said the information was released now because it was just uncovered in Pakistan.

"We don't do politics in the Department of Homeland Security," Ridge said. "Our job is to identify the threat."

His comments follow a meeting with the governors of New York and New Jersey, and New York Mayor Michael Bloomberg in New York City at Citigroup Center in Manhattan.

Citigroup is among several buildings reportedly cited as terror targets. Other buildings include:

• The New York Stock Exchange in New York City
• The International Monetary Fund in Washington
• The World Bank buildings in Washington
• Prudential Financial in Newark, N.J.

Ridge raised the terror alert on Sunday from "elevated" (yellow) to "high" (orange). He said officials had received "new" information that attacks could take place at what Ridge called "iconic" financial institutions.

While this isn't the first time the terror alert has been raised a level, officials say this threat is the most specific to date since 9/11.

Ridge said the attacks could be carried out in three ways -- as a physical attack, an outside cyber-attack, or an attack from the inside to disrupt operations. He added that the apparent "preferred method of attack" was a truck or car bombing.

U.S. officials say the documents and pictures that led to the terror alert largely came from Mohammad Naeem Noor Khan, also known as Abu Talha, who was captured in mid-July in Pakistan.

A Pakistani intelligence official alleges that Khan, a computer and communications expert, sent messages to suspected al Qaeda members using code words.

Michel Juneau-Katsuya, a former agent with the Canadian Security Intelligence Service, said he expects more and more of these terror alerts to be issued leading up to the Republic Convention in September, and the U.S. election in November.

"It is the insidious nature of terrorism, it can hit at any time and any place," he told Canada AM.

CTV's Denelle Balfour, in an interview with Canada AM, said workers will still face tight security when they go to work on Tuesday, despite a lack of terror activity on Monday.

"New Yorkers are taking all of this in stride," she said. "It's business as usual."

In related news, the pedestal in the Statue of Liberty is reopening Tuesday to the public. It was closed after the 9/11 attacks.

With files from The Associated Press