Islamabad says it will probe potential links between militants operating in Pakistan and the man accused of trying to blow up a car in New York City.
The suspect, Faisal Shahzad, has told U.S. investigators that he trained in the lawless tribal areas of Waziristan, where both Al-Qaeda and the Pakistani Taliban operate.
Pakistani Interior Minister Rehman Malik said Islamabad had received a formal request for an investigation from the United States.
Malik also stressed that only Pakistani investigators would be permitted to interview Shahzad's relatives and other associates.
The Pakistani-American Shahzad is the main suspect in the May 1 failed Times Square car bombing.
The Taliban at first claimed responsibility, but later backed away from the claim.
Pakistan had already promised to cooperate with the investigation and has detained at least four people with alleged connections to Shahzad.
compiled from agency reports