Relatives carry the coffin of Pakistani journalist Syed Saleem Shahzad during his funeral
The US military's top officer said that Islamabad may have sanctioned the killing of a Pakistani journalist, voicing grave concern over the murder.
Asked about media reports that the Pakistani government
approved the killing of the reporter, Admiral Mike Mullen on Thursday said: "I haven't seen anything that would disabuse that report."
He said he was "concerned" about the incident and suggested other reporters had suffered a similar fate in the past.
"His (death) isn't the first. For whatever reason, it has been used as a method historically," Mullen told reporters at a Pentagon Press Association luncheon.
While acknowledging Pakistani officials have denied the government had any role in the death of Saleem Shahzad, Mullen said the episode raised worrying questions about the country's current course.
"It's not a way to move ahead. It's a way to continue to quite frankly spiral in the wrong direction," said Mullen, who has held numerous meetings with Pakistani counterparts during his tenure as chairman of the US Joint Chiefs of Staff.
Mullen's remarks are sure to aggravate already strained relations between the uneasy allies after the US raid north of Islamabad in May that killed Al-Qaeda chief Osama bin Laden, which was carried out without Pakistan's knowledge.
Asked if Pakistan's intelligence service had been behind the killing of the journalist, Mullen said he could not confirm that allegation.
The New York Times, citing US officials, reported Monday that the powerful Inter-Services Intelligence agency ordered the killing of Shahzad to muzzle criticism.
The ISI has denied as "baseless" allegations that it was involved in the murder of Shahzad, who worked for an Italian news agency and a Hong Kong-registered news site.
Shahzad, who had reported about militants infiltrating the military, went missing en route to a television talk show and his body was found May 31 south of the capital, bearing marks of torture.
He disappeared two days after writing an investigative report in Asia Times Online saying Al-Qaeda carried out a recent attack on a naval air base to avenge the arrest of naval officials held on suspicion of links to the global terror network.
Pakistani Prime Minister Yousuf Raza Gilani has ordered an inquiry into the kidnapping and murder, pledging that the culprits would be "brought to book."
Citing mounting tensions over the past year, Mullen acknowledged the US relationship with Pakistan is "under extraordinary pressure."
Even before the unilateral bin Laden raid, ties had become strained, Mullen said, particularly over the arrest of a CIA contractor in Pakistan who was charged with double murder before eventually being released.
"So we've been through a very, very rough time," he said.
Washington was "committed to sustaining that relationship," he continued.
"But we recognize it's under great stress right now and we need to see our way through it."
The military's top-ranking officer, who is due to step down at the end of September, confirmed the US military presence in Pakistan had been dramatically scaled back at Islamabad's request.
Despite growing frustration in the US administration over Pakistan's failure to crack down on militant sanctuaries near the Afghan border, Mullen said it would be a serious mistake to cut off financial aid to Islamabad, as some American lawmakers have urged.
"I think that would be a disaster now and it would be a disaster in the future," he said.