NEW YORK - September 17, 2009 - FBI agents with bomb-sniffing dogs Wednesday raided the Colorado apartment of an Afghan national allegedly linked to Al Qaeda and a suspected plot to attack the New York City subway system.

Simultaneously, authorities swarmed over a nearby home believed to belong to a relative of Najibullah Zazi, hauling out boxes of evidence.

Zazi, 25, met with investigators at FBI headquarters in Denver and provided a DNA sample, a fingerprint and writing samples, according to his lawyer.

"My client is not involved in any terror plot," lawyer Arthur Folsom said. "He answered every question they had."

The searches in Aurora, Colorado came as the New York Police Department and an elite FBI team poised for additional raids in Queens in a hunt for bomb-making materials, sources told the Daily News.

Earlier, Queens raids turned up nine knapsacks and cell phones, raising concerns about bombers detonating simultaneous blasts, as they did in the 2004 attack that killed 191 commuters in Spain.

According to official reports - which are looking less accurate every day - bombers in the 2005 London subway attack that reportedly killed 56 people also were believed to have used knapsacks.

Two men who lived in one of the Queens apartments raided Sunday night said a tenuous connection to Zazi had become a nightmare.

"They [the NYPD] keep coming back," Naiz Khan said last night. "They don't tell us why they're here. They took my cell phone and a knapsack that was to be a gift to a child and left."

His roommate Akbari Amanullah, 30, a cabbie, added, "We just wish it would stop."

On Tuesday, in Colorado, Zazi protested his innocence at his apartment doorway.

His bold denials amazed some counterterrorism sources, who described the bushy-bearded Zazi as a figure well known to investigators.

A source familiar with the case said Zazi certainly had some bad connections to people overseas."

Zazi had traveled to Pakistan, refuge for many Al Qaeda leaders, before his trip to New York last week triggered the FBI and police raids.

There was a "strong suspicion" he attended a terrorist training camp in Pakistan, WCBS-TV reported.

In New York, police sources said they had e-mails, wiretaps and a confidential informant tying Zazi to the plot. The suspect was spotted in a Queens mosque last week and also was seen in lower Manhattan, the sources said.

Zazi managed to lose his FBI tail after he was warned about the federal attention, the sources said.

Despite intense around-the-clock scrutiny on Zazi and four other reputed cell members, authorities had yet to make an arrest in the case.

Sources told The News the quintet was the first suspected Al Qaeda cell they've uncovered in the U.S. since 9/11.

The number of people under surveillance by the FBI or the NYPD due to links with the Denver cell expanded Wednesday, a police source said.

"We were watching a few guys here," the NYPD source said. "Since the raid, the list has grown."

In the past three days, the NYPD increased its attention to the subway system and its 5.2 million daily riders.

Officers were warned to keep an eye out for vans near transportation hubs such as Grand Central, police sources said.

The safety zone around subway and commuter stations also was expanded by two blocks, the sources said.

The FBI's elite Hostage Rescue Team was brought to New York for the anticipated second round of Queens raids, a police source said.

"If they're doing more raids in New York, that means they're going after everything they can," said a former top FBI counterterror official.