New York: Chinese military engineers were "probably" given access by Pakistan to the wreckage of the US stealth helicopter that had crashed in Osama bin Laden's compound during the Abbottabad raid and Chinese engineers might even have walked away with samples, a media report said.

The US Navy SEALs who conducted the May 2 operation that killed the al Qaeda leader had tried to destroy the chopper after it malfunctioned but its tail section had remained
largely intact.

The crashed helicopter appeared to have never-before-seen superior technology, including a special coating designed to elude air defences and radars.

"American spy agencies have concluded that it is likely that Chinese engineers — at the invitation of Pakistani intelligence operatives — took detailed photographs of the severed tail of the Black Hawk helicopter equipped with classified technology designed to elude radar," a report in a leading daily said.

Citing American officials familiar with classified intelligence assessments, the report said "such cooperation with China would be provocative, providing further evidence of the depths of Pakistan's anger over the bin Laden raid, which was carried out without Pakistan's approval".

"In the days after the raid that killed Osama bin Laden, Pakistan's intelligence service probably allowed Chinese military engineers to examine the wreckage of a stealth American helicopter," the report said.

A person with knowledge of the intelligence assessments said that the American case was based mostly on "intercepted conversations" in which Pakistani officials discussed inviting the Chinese to the crash site.

The person familiar with the matter characterized intelligence officials as being "certain" that Chinese engineers were able to photograph the helicopter and even walk away with samples of the wreckage.

American officials however cautioned that they did not yet have "definitive proof" that the Chinese were allowed to visit Abbottabad even though Pakistani officials had been directly confronted about the American intelligence.

Pakistani officials had denied showing the advanced helicopter technology to other foreign governments, the report added.

Pakistan has a close military relationship with China, and large numbers of Chinese engineers work at military bases inside Pakistan.

Pakistani officials have even suggested that the Chinese Navy might eventually have its own base along Pakistan's coastline, it said.

The US had been worried about the secret technology being leaked to Pakistan.

Pakistani officials had also made a high-profile trip to Beijing shortly after the Abbottabad raid, "part of a not-so-subtle campaign to show the strength of Pakistan's alliance with China amid faltering relations between Washington and Islamabad," the report said.

The wreckage of the helicopter had been shipped back to the United States, according to American officials.