In a report on the spread of weapons technology submitted to the US Congress on Wednesday, the CIA said during the period July 1-December 31, 1971, Beijing narrowly interpreted its bilateral non-proliferation commitment with the US.

China made pledges to the US not to assist any country acquire or develop nuclear weapons.

"We cannot rule out some continued contacts subsequent to the pledge between the Chinese entities, perhaps without Beijing's knowledge or permission, and entities associated with Pakistan's nuclear weapons programme," the report said.

As far as missiles are concerned, the CIA pointed out that Beijing had promised not to sell Missile Technology Control Regime category-I systems but has not recognised the regime's key technology annex.

In November 2000, China also agreed to not assist any country in developing ballistic missiles that could be used to deliver nuclear weapons, and to enact a comprehensive missile-related export control system.

"Chinese entities provided Pakistan with missile-related technical assistance during the reporting period. Pakistan has been moving towards serial production of solid-propellant short-range ballistic missiles with their help.

"Pakistan needs continued Chinese assistance to support development of the two-stage Shaheen-II MRBM. In addition, firms in China have provided dual-use missile-related items, raw material and assistance to several other countries of proliferation concern, such as Iran, North Korea and Libya."

Beijing and Islamabad have also negotiated the sale of 40 F-7 fighters to Pakistan, the CIA report noted.