The FBI is planning more raids in New York City amid ongoing fears of a subway bombing plot by a Denver-based terror cell with ties to Al Qaeda, the New York Daily News reported.

On the heels of raids Monday on several Queens apartments, the bureau's Hostage Rescue Team is gearing up for additional raids, police sources told the Daily News, and authorities in Colorado on Wednesday searched the apartment of one of the suspects.

Counterterrorism officials have warned police departments nationwide to look out for evidence of homemade bombs and bomb-making material in the wake of the anti-terror raids.

One of the raids Monday uncovered nine backpacks and cell phones, reminiscent of gear used in the 2004 attacks in Madrid that killed 191 people, triggering fears of a similar attack on New York's 5.2 million daily subway riders, one source told the Daily News.

Federal agents Wednesday searched the Denver home of Najibullah Zazi, identified by law enforcement officials after the initial raids as possibly having ties to Al Qaeda.

Zazi has denied being the central figure in the investigation.

Click here to read more on this story from the New York Daily News.

The Associated Press contributed to this report.