¡¡WASHINGTON, Aug. 3 (Xinhuanet) -- Much of the information that ledthe US government in recent days to raise the terror alert for five financial centers in New York City, northern New Jersey and Washington was three or four years old, media reports here said Tuesday.

    The reports quoted intelligence and law enforcement officials as saying that they had not yet found concrete evidence that a terrorist plot or preparatory surveillance operations were still underway.

    But the officials continued to regard the information as significant and troubling because reconnaissance by al Qaeda had provided the terrorist organization with the knowledge necessary to carry out attacks against sites in Manhattan, Washington and elsewhere.

    Al Qaeda had often struck years after its operatives began surveillance of an intended target, the officials said.

    "You could say that the bulk of this information is old, but weknow that al Qaeda collects, collects, collects until they're comfortable," one senior government official was quoted by The NewYork Times as saying. "Only then do they carry out an operation."

    The newspaper reports came after White House homeland security adviser Frances Fragos Townsend said on Monday that surveillance reports, apparently collected by al Qaeda operatives, had been gathered in 2000 and 2001. But, she added, information might have been updated as recently as January.

    "There is nothing right now that we're hearing that is new," a report in The Washington Post quoted one senior law enforcement official who was briefed on the alert as saying. "Why did we go tothis level...I still don't know."

    On Sunday, Homeland Security Secretary Tom Ridge raised the terrorist threat level in some financial centers in Washington, New York City and northern New Jersey saying intelligence from "multiple reporting streams" was "alarming in both the amount and specificity of the information." Enditem