spokesman said: "It was Islamabad."
Prosecutors charged Shahzad, 30, a naturalised US citizen born in Pakistan, with five counts, including attempting to use a weapon of mass destruction and trying to kill and maim people within the United States. He faces a life sentence if convicted.
Shahzad was arrested on Monday after he was taken off an Emirates plane that was about to depart for Dubai, a major transit hub. Hours later, several of his relatives were arrested in Pakistan, security sources said.
Emirates said three people were removed from the flight but two were later cleared and allowed on board. All passengers were deplaned and screened before the plane left for Dubai.
US authorities are investigating whether Emirates made a mistake in letting Shahzad on one of its aircraft.
The former financial analyst was accused of driving a crude homemade bomb of gasoline, propane gas, fireworks and fertiliser into a busy Times Square on a warm Saturday evening.
The bomb was in a sports utility vehicle that prosecutors said Shahzad bought for $1,300 in cash. Prosecutors said Shahzad admitted to the bomb attempt and to receiving training in a Taliban and al Qaeda stronghold in Pakistan.
CALM MOOD AS PASSENGERS PULLED FROM FLIGHT
Passengers on the New York-to-Dubai flight described the mood on the Emirates plane as calm and controlled as police boarded before takeoff to remove several passengers.
"Honestly nobody panicked, everybody was so calm, and everybody was so quiet. There were a lot of people who had connecting flights, they just wanted to get the hell out of JFK," said Egyptian Azza Abou al-Magd, who was on the plane.
She told Reuters that one of those removed from the flight was whisked out by armed police officers that confiscated the man's phone and politely and quietly escorted him off the plane.
The Taliban in Pakistan claimed responsibility for the bomb attempt, saying it was to avenge the killing of two top al Qaeda leaders in Iraq and for U.S. interference in Muslim countries.
While some U.S. officials were sceptical about the claim, Pakistani Foreign Minister Shah Mehmood Qureshi told CBS News he believed the failed attack was retaliation for the United States targeting Taliban followers.
Passengers on the Emirates flight said they were not informed of the magnitude of what was happening on the plane.
"They didn't tell us: 'Hey listen guys we have someone'. We didn't know what was going on, when we went back to the taxi and then we went back to the airport that was when we became somewhat concerned," Faye Roy, a passenger, said.
"I called a friend at home and said turn on CNN and tell me what's going on on my plane and he told me," she said after the delayed flight arrived in Dubai on Wednesday morning.
Another passenger, Samir al-Ammari, said: "I was worried. I was planning to cancel the flight and take another. ... It was very difficult when you hear about something like this."