WASHINGTON, March 8: Pakistan may have given China access to a key US fighter jet at the height of the Vietnam War in a quid pro quo transaction that may have endangered the lives of American pilots , according to US government documents made public here.

The revelation, contained in a secret December 1968 memorandum written by George Denney, deputy director of intelligence and research at the State Department, comes as the administration of President George W. Bush seeks to broaden security ties to Islamabad as part of the war on terror.

Congress also currently has growing questions about a nuclear black market network run by top Pakistani scientist Abdul Qadeer Khan and how much authorities in Islamabad knew about it.

The Denney memo and other documents obtained by the National Security Archive, a freedom of information group, and released over the weekend paint a picture of deep dissatisfaction with Pakistan within the US foreign policy community, which felt deceived by the country's leaders.

"In July 1968 an intelligence source revealed that Chinese technicians had been allowed to examine US-provided F-104 aircraft at Pakistan's Sargodha Air Base and to collect F-104 spare parts and material samples which were taken back to China for analysis," Denney wrote to then-secretary of state Dean Rusk.

He pointed out that he believed the Pakistani action "violates the terms of acceptance" that Pakistan signed when it took delivery of the jets. Citing the same intelligence source, Denney noted that the Chinese had been also allowed to take back home for examination a complete F-104 engine, including key parts of its innovative fuel control system.

The deputy chief of intelligence hastened to reassure his boss that Beijing "probably will not derive great advantage" from such unprecedented access, but warned that "a precedent appears to have been set, and China can be expected to make further requests along the same lines."

Beijing was a crucial ally of Hanoi during the Vietnam War, and intelligence experts believe any information gleaned by the Chinese about the F-104 Star fighter, one of the mainstays in the US Air Force at the time, had likely found its way into Vietnamese hands.

The F-104 was designed in the wake of the Korean War at Lockheed's super secret "Skunk Works" facility to challenge leading Soviet-made fighter jets. Dubbed by pilots "a missile with a man in it," the Star fighter was the first aircraft to hold simultaneous official world records for speed, altitude and time-to-climb.

For these reasons the North Vietnamese Air Force usually avoided direct engagements with the F-104, according to US veterans, but actively sought information about the plane.

The alleged Pakistani favour followed massive deliveries of Chinese weapons that Pakistan needed to boost its arsenal against India, according to the document. -AFP