New York City is mobilizing hundreds of police officers after law enforcement officials received report of a “credible threat” to the subway system.

Sources told ABC News 19 terrorist operatives have been deployed to the city to place bombs in the subway.

A law enforcement official told the Associated Press, on condition of anonymity prior to an announcement, that the threat is “specific to place, time and method.”

Rep. Peter King of New York, chairman of the House Homeland Security Committee, confirmed the report.

“Obviously, this is a significant threat,” he said.

The planned attack is said to be timed to the start of the Muslim holy month of Ramadan and to the Jewish High Holidays.

Officers have been dispatched to patrol every subway station in Manhattan and are expected to be kept on 12-hour tours over the weekend.

While the police department is taking the threat seriously, the public is being urged to not be alarmed. Though the source is credible, the information has not been verified, officials say.

Mayor Michael R. Bloomberg said it was the most detailed threat he has seen against the city’s subway system.

“I wanted to assure New Yorkers that we have done and will continue to do everything we can to protect the city,” Bloomberg said. “We will spare no resource. We will spare no expense.”

According to ABC News, the threat was disclosed when three Iraqi insurgents were arrested several days ago during a raid by a joint FBI-CIA team.

The plot was deemed credible because the information slipped out during the arrest.

NYPD said that after several days work, they have become increasingly concerned because they can’t discredit the initial source.

The 19 operatives were to place improvised explosive devices in the subways using briefcases, ABC News said.

Police officers already were on heightened alert for the Jewish holiday of Rosh Hashana this week.

As WorldNetDaily reported, al-Qaida has been plotting major attacks for Ramadan, according to Paul Williams, author of “The Al Qaeda Connection.”

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