Pakistani intelligence denies Chinese military was allowed to photograph and take samples from wreckage of Black Hawk

US officials believe Pakistan has secretly allowed the Chinese military to examine the wreckage of the helicopter destroyed during the raid to kill Osama bin Laden in May.

American intelligence sources told the New York Times that Pakistan had allowed Chinese officials to photograph and take samples from the Black Hawk stealth helicopter that crashed on the grounds of bin Laden's house in Abbottabad. The information was based on intercepted phone calls, said the paper.

The helicopter was then blown up by US special forces to prevent it falling into foreign hands. The electronics systems were completely destroyed but the tail section of the aircraft was left largely intact.

It sat propped against a wall of the compound in full view of curious onlookers for several days. The helicopter tail immediately attracted attention because of its differences from other Black Hawks, including the outer skin and curved shape which appeared to be designed to help the aircraft avoid detection by radar.

In the days following the raid Chinese military officials reportedly took away samples of the helicopter's skin and photographed the design.

A Pakistani intelligence official, who declined to be named, called the story "baseless", adding "speculation … is counter-productive in building relations". In the wake of Bin Laden's death, however, Pakistani officials angered at not being brought in on the raid hinted that the Chinese might be given access to the wreckage.

Islamabad maintains a close relationship with the Chinese military and permits Chinese engineers to work on Pakistani bases. The two countries also have an increasingly close economic relationship, with Chinese companies investing heavily in infrastructure and telecommunications in Pakistan.

If the reports are accurate they are likely to fuel the deepening tension between Islamabad and Washington over the raid. Permitting Chinese officials to examine the secret technology may be viewed as particularly provocative by some politicians in Washington already sceptical over Pakistan's claims not to have known that Bin Laden was living in Abbottabad for years.

The tail section was moved to the US two weeks after the raid following a visit to Pakistan by former presidential candidate Senator John Kerry. While there he warned that the US might cut aid to the country.