NEW YORK, Oct. 10 (Xinhuanet) -- New York Mayor Michael Bloomberg said on Monday it will cut back on the increased security implemented in the subways since late last week.

    The announcement came as the Federal Bureau of Investigation (FBI) expressed serious doubts over a real terrorist threat to blowup New York City's subway system.

    A spokesman for the FBI said Monday that the information about the potential threat, which included the possibility that terrorists planned to use timed or remote-controlled explosives hidden in briefcases, suitcases, and under strollers in the mass transit system, has not panned out.

    Bloomberg defended the city's decision to beef up security in transit system and said he had no regret.

    "Since the period of the threat now seems to be passing, I think over the immediate future we'll slowly be winding down the enhanced security," Bloomberg said Monday. "But we stay at level orange in this city we have since 9/11. We're going to take every single threat that has any chance of being credible seriously and do exactly what we did."

    State and local authorities learned of the potential threat in a memo issued by the Department of Homeland Security Wednesday. The memo says the attack might be carried out on or around Sunday by operatives, "who may be in the New York City area."

    Throughout the weekend, police officers flooded subways and checked passengers' bags, a reaction Mayor Michael Bloomberg said was absolutely justified.

    Interrogations of suspects captured in Iraq Thursday and Friday after an informant's tip about bomb-laden suitcases and baby carriages have yet to yield evidence that the plot was real, officials said.

    The informant who prompted the plot investigation has provided a mix of true and false information in past investigations, Police Commissioner Ray Kelly said on CNN.

    The commissioner said he remained confident that the city acted properly.

    "This threat was very, very specific. It had specific time, specific object and modality. So, you know, we had to do what we did," Kelly said. Enditem