The United States says it has evidence that the Pakistani Taliban was behind the attempted car bombing in New York's Times Square.
Attorney General Eric Holder said they helped to facilitate the plot, and "probably helped finance it".
US officials had previously rejected claims by the group that it was behind the 1 May plot.
A Pakistani-born US citizen has been charged with the attempted bombing in New York's tourist quarter a week ago.
Faisal Shazhad, 30, from Bridgeport, Connecticut, has co-operated with investigators, and admits receiving bomb-making training in the Pakistan region of Waziristan, prosecutors have said.
"We've now developed evidence that shows that the Pakistani Taliban was behind the attack," Mr Holder said on ABC television's Sunday current affairs talk show "This Week".
"We know that they helped facilitate it. We know that they probably helped finance it, and that [Shahzad] was working at their direction".
Mr Holder said there was nothing to suggest the government of Pakistan was aware of the plot.
He also said the Obama administration was satisfied for now with the level of co-operation it was receiving from the Pakistani authorities into the investigation of the attempted bombing.
The bomb was discovered last Saturday evening in Times Square, which was busy with tourists and theatregoers at the time.
The bomb was discovered and dismantled after a street-vendor noticed smoke coming from a Nissan Pathfinder, which had been left with its engine running and hazard lights flashing.
The unexploded bomb left crucial evidence intact that detectives used to trace Mr Shahzad.
BBC News
