Pakistan has rejected allegations by the top US military officer that the government sanctioned the killing of a journalist who wrote about the country's powerful security establishment.
The claim was "extremely irresponsible," the Pakistani state-run news agency said.
Claims over the death of Saleem Shahzad have added to the strain on US-Pakistan relations, which have deteriorated badly since the American raid that killed Osama bin Laden on May 2.
Shahzad's tortured body was found in late May after he told friends he had been threatened by Pakistan's Inter-Services Intelligence agency, a spy unit that is notorious for harassing reporters.
The ISI has denied it had anything to do with killing Shahzad, but the suspicions have persisted and prompted unusual levels of public criticism of the spy agency.
Shahzad's death also added to the pressure on the Pakistani military since the unilateral US raid against the al Qaida chief, which left it humiliated.
On Thursday, US joint chiefs of staff chairman Admiral Mike Mullen said he believed the Pakistani government "sanctioned" Shahzad's killing.
Although Admiral Mullen acknowledged he could not directly tie the killing to the ISI, he was the first US official to make such a public allegation.
The state-run Associated Press of Pakistan issued a statement hours later in which an unnamed government spokesman called Mullen's allegations "extremely irresponsible" and said that it "will not help in investigating the issue".
Pakistan was the deadliest country for journalists in 2010, with at least eight killed in the line of duty, according to the New York-based Committee to Protect Journalists.