Faisal Shahzad was arrested Monday night at JFK International Airport aboard a plane scheduled to fly to Dubai, United Arab Emirates. (CNN via Orkut.com)

The investigation into the attempted bombing in New York's Times Square is turning to Pakistan, where a number of the suspect's relatives and associates have been detained, reports say.

Faisal Shahzad, a 30-year-old naturalized U.S. citizen from Pakistan, was arrested at JFK International Airport in New York on Monday night in connection with Saturday night's failed bombing.

He faces five charges, including attempting to use a weapon of mass destruction. The New York Times reported Wednesday that Shahzad has waived his right to a speedy arraignment on the charges — suggesting he is co-operating with authorities — and that no court date has been scheduled.

Shahzad has reportedly confessed to receiving bomb training in Pakistan, prompting authorities to expand the investigation and examine any possible extremist group connections.

Investigators were trying to determine if Shahzad's claim of getting training in Pakistan was true, but law enforcement officials who spoke on condition of anonymity said they had not been able to verify that statement yet.

Shahzad's parents, who are believed to live in northern Pakistan, are also being held by the Pakistani government, freelance journalist Declan Walsh reported.

"As we understand it, many of these people are being jointly questioned by both U.S. and Pakistani authorities," Walsh said.

The Pakistani Taliban claimed responsibility for Saturday night's failed bombing in a video message released over the weekend.

But earlier Wednesday, a Pakistani military spokesman cast doubt on claims that the Taliban were behind the botched bombing.

Maj.-Gen. Athar Abbas, chief spokesman for Pakistan's military, said the claim should be "taken with a pinch of salt."

"Anybody can claim anything, but whether the organization has that kind of reach is questionable. I don't think they have the capacity to reach the next level," he said.

No-fly list rules changing

Meanwhile, the U.S. government is making changes to its no-fly list regulations after Shahzad was able to board a plane bound for Dubai, despite being named on a no-fly list.

Effective immediately, airlines will have to check the updated list within two hours of being notified of changes, according to a U.S. Homeland Security official who spoke to The Associated Press on the condition of anonymity because he was not authorized to publicly discuss the policy change.

Shahzad, who had recently returned to the U.S. from a five-month trip to Pakistan, was arrested at JFK International Airport in New York on Monday aboard a plane to Dubai, United Arab Emirates.

Federal officials put Shahzad on a no-fly list just hours before he was arrested, but Emirates Airlines didn't initially notice that he had been placed on the list, allowing him to board the plane despite the ban.

The investigation began Saturday when a 1993 Nissan Pathfinder sport utility vehicle was found in Times Square.

Investigators found in the SUV three propane tanks, a pair of full 19-litre gasoline containers and two clocks with batteries, electrical wire and other components. The clocks were said to have been connected to a can filled with fireworks, which were apparently meant to ignite the gasoline and, ultimately, the propane.

Authorities traced the SUV back to a previous owner and now allege Shahzad bought it about three weeks ago, using cash.

Police said Wednesday that Shahzad bought a rifle legally in Connecticut two months ago.

Shelton, Conn., police Chief Joel Hurliman said the owner of Valley Firearms confirmed Shahzad bought the rifle and passed a 14-day waiting period for the background check.

Earlier, New York police Commissioner Raymond Kelly said Shahzad had driven to JFK airport with a gun. Kelly said the gun was found in a car Shahzad left at the airport.

With files from The Associated Press