Faisal Shahzad, the Pakistani-American arrested in connection with the failed Times Square car bomb attack, has admitted he had attended a terrorist training camp in Pakistan, the Federal Bureau of Investigation said.

FBI also said that Shahzad, 30, confessed he had attempted to detonate a bomb at Times Square. Pakistani authorities have meanwhile detained seven persons from all across the country for their alleged links with Shahzad, who told the FBI that he had also received bomb-making training at the terror camp in Waziristan, a lawless tribal region where the Pakistani Taliban operates with near impunity.

The training raised the possibility of a coordinated international plot for an attack. In a ten-page complaint filed on Tuesday before the Court of Judge Nathaniel Fox, Southern District of New York, the FBI alleged Shahzad travelled from Connecticut to New York on a sports-utility vehicle that was laden with a bomb.

Shahzad was arrested from the New York's John F Kennedy Airport on Monday night when he was trying to flee the country.

Image: An undated image, obtained from orkut.com, on Tuesday, shows Faisal Shahzad

Photographs: Reuters Text: PTI

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Shahzad, a resident of Connecticut man and a naturalised US citizen, is the son of a retired Air Vice Marshal of the Pakistan Air Force. His parents live in Peshawar while his ancestral home is in the Pubbi area of Khyber-Pakhtoonkhwa province.

US Attorney General Eric Holder told mediapersons in New York that Shahzad was co-operating with the federal investigating agencies and was providing useful information.

"After the arrest Shahzad admitted that he had attempted to detonate a bomb in Times Square. He also admitted that he had recently received bomb-making training in Waziristan, Pakistan," the FBI said.

In Karachi, Security officials, who declined to be named, confirmed at least two detentions but did not reveal further details. According to other sources, a person identified as Tauseef Ahmed was one of the detainees.

Ahmed had made several contacts with Faisal in the last few weeks and had even gone to the US sometime back on his invitation, they said. The other person picked up was related to Faisal who originally belonged to the NWFP, they said.

Image: A view of the former home of Faisal Shahzad on Sheridan Street in Bridgeport, Connecticut Photograph: Mike Segar / Reuters

The US federal complaint said Shahzad, who gained US citizenship in April last year, returned from Pakistan on February 3.

He had arrived on a one-way ticket. During an immigration inspection, Shahzad told officials that he had been in Pakistan for at least five months to visit his parents.

He indicated that he intended to stay in a motel in Connecticut while he looked for a place to live and a job. Shahzad further advised his wife to remain behind in Pakistan, the FBI told the court. In addition, Shahzad admitted that he had brought the Pathfinder to Times Square and attempted to detonate it.

Shahzad also noted that he had driven a particular car to the airport on May 3 and stated that the car contained a gun, the FBI said, adding the gun was recovered from his car.

"Shahzad, after receiving bomb-making training in Waziristan, Pakistan travelled to the US, transported a sports utility vehicle to the vicinity of 45th Street and Seventh Avenue in Manhattan, New York, and attempted to detonate explosive and incendiary devices located inside the sports utility vehicle," the complaint stated.

Image: FBI investigators remove evidence from the former home of  Faisal Shahzad in Connecticut, on Tuesday Photograph: Mike Segar

Following his arrest late Monday night, the FBI said Shahzad used a pre-paid cellular telephone, which has not been used since April 28, both to call a fireworks store and to receive a series of calls from Pakistan following his purchase of Nissan Pathfinder.

Meanwhile, Pakistan authorities have detained seven men from different parts of the country for their alleged links with Faisal Shahzad.

A top police official in Punjab province told PTI that at least seven suspects had been taken into custody in Lahore, Rawalpindi, Faisalabad and Karachi and shifted to an undisclosed location for interrogation.

He did not confirm whether the detained suspects had links to the Taliban or Al Qaeda. "I can only confirm the detentions at the moment. The intelligence agencies are in contact with US authorities about this matter," the officer said.

Image: A man walks near a house, which allegedly belongs to the family of Faisal Shahzad at a village in Pabbi, a small town near Peshawar, on Wednesday Photograph: K Parvez / Reuters

Meanwhile, Pakistani Taliban chief Hakimullah Mehsud has written a letter to the sister of Aafia Siddiqui, a Pakistani convicted for attempted murder by an American court, saying he would carry out a 'memorable' attack against the US.

The Tehrik-e-Taliban Pakistan chief 'threatened a memorable response against the United States' in the letter he wrote to Fouzia Siddiqui nearly two months ago, Dawn News channel reported.

On the basis of this letter, the channel contended that Hakimullah may have had a hand in the botched car bombing in New York City that resulted in the arrest of Faisal Shahzad.

In the letter, Hakimullah declared the sister of the incarcerated Aafia Siddiqui as his own sister and assured her of all possible cooperation.

Image: A surveillance photo shows a man with a bag removing  a shirt near Times Square where he is suspected of leaving a car bomb set up in a Nissan Pathfinder in Times Square in this New York Police Department surveillance footage released to Reuters on Monday

Photograph: Reuters