Federal agents on Wednesday searched the home of a suburban Denver man identified by law enforcement as having a possible link to al-Qaida.

FBI special agent Kathleen Wright confirmed that agents and sheriff's deputies had a search warrant and had entered the home of Najibullah Zazi. It wasn't immediately known if Zazi was at home at the time of Wednesday's search.

Zazi has denied he's a central figure in a terrorism investigation that fed fears of a possible bomb plot and led to several police raids in New York City on Monday.

One agent wearing protective clothing escorted a dog belonging to the Bureau of Alcohol, Tobacco, Firearms and Explosives into Zazi's apartment. Another wore a shirt with the words "FBI Evidence Response Team" on it.

Other agents wearing FBI jackets stood outside the building along with Arapahoe County sheriff's deputies.

Two law enforcement officials told the AP that a joint FBI- New York Police Department task force had put Zazi under surveillance because of suspected links to terrorism organizations.

The task force also feared Zazi was involved in a potential plot involving homemade hydrogen peroxide-based explosives like those cited in an intelligence warning issued Monday, said the officials, who spoke on anonymity because they were not authorized to speak about the investigation.

After Zazi traveled to New York City over the weekend, FBI agents and police officers armed with search warrants seeking bomb materials searched three apartments and questioned residents in a predominantly Asian neighborhood in Queens.

Naiz Khan, an Afghan immigrant who grew up with Zazi in New York City, said the FBI questioned him for about two hours about Zazi, whom he said stayed at his apartment last week.

No arrests were announced, and the FBI and NYPD have refused to discuss the case.

New York Police Commissioner Raymond Kelly and FBI Director Robert Mueller said Wednesday there are no specific terrorist threats to the city.