Pakistan gave China access to the previously unknown U.S. “stealth” helicopter that crashed during the commando raid that killed Osama bin Laden in May despite explicit requests from the CIA not to, the Financial Times reported Sunday.

The disclosure, if confirmed, is likely to further shake the U.S.-Pakistan relationship, which has been improving slightly of late after hitting its lowest point in decades following the bin Laden killing in a Pakistani garrison city.

During the raid, one of two modified Black Hawk helicopters, thought to employ unknown stealth capability, malfunctioned and crashed, forcing the commandos to abandon it.

“The U.S. now has information that Pakistan, particularly the ISI, gave access to the Chinese military to the downed helicopter in Abbottabad,” the paper quoted a person “in intelligence circles” as saying on its Web site.

The ISI, the Inter-Services Intelligence Directorate, is Pakistan’s top spy agency.

The report said Pakistan, which enjoys a close relationship with China, allowed Chinese intelligence officials to take pictures of the crashed aircraft as well as samples of its special “skin,” which allowed the helicopter to evade Pakistani radar.

One U.S. official, speaking on the condition of anonymity, told Reuters that there was reason to believe that Pakistan had let the Chinese inspect the aircraft. But the official could not confirm whether it had happened.

No one from the Pakistani army was available for comment, but the ISI denied the report. The paper said Pakistan’s top general, army chief Ashfaq Kayani, denied that China had been given access to the aircraft.

The helicopter’s surviving tail section, photos of which were widely distributed on the Internet, was returned to the United States after a trip by Sen. John F. Kerry (D-Mass.) in May, a spokesman for the U.S. Embassy told Reuters.

Shortly after the raid, Pakistan hinted that it might give China access to the helicopter, given Pakistan’s fury over the raid, which it considers a grievous violation of its sovereignty.

In an incident such as the helicopter crash, it is standard U.S. procedure to destroy sophisticated technology such as encrypted communications and navigation computers.