Neither China nor the US government has been candid with the public on Beijing's ``significant'' aid to Islamabad in both nuclear weapon and missile fields, the California-based Monterey institute of international studies said.

Since then, China has supplied Pakistan with a variety of nuclear products and services, ranging from uranium enrichment technology to research and power reactors, it said, adding China allegedly involved Pakistani scientists in a nuclear test at its Lop Nor test site in 1989.

Yet China has continued to insist that it ``does not encourage nuclear proliferation'' and that its nuclear cooperation with Pakistan was ``purely for peaceful purposes,'' the report pointed out.

The most recentproliferation controversy regarding China's nuclear trade with Pakistan concerned the late 1995 export of about 5,000 specially designed ring magnets to an un-safeguarded Pakistani nuclear laboratory, allegedly a nuclear weapons lab.

In talks with US officials, China eventually conceded the sale had taken place but argued that it occurred without the knowledge or consent of the central government.

On China's missile trade with Pakistan, the institute said, the US had announced in April 1991 that it had discovered the transfer of M-11s to Islamabad

China insisted that it had never transferred medium range missiles to Pakistan but a month later it admitted selling a "small number" of M-11s, which Beijing argued was not covered by the Missile Technology Control Regime (MTCR)-related sanctions, the report said.

Washington responded with imposing sanctions on computer sales to China, but secretary of state James Baker accepted verbal assurances that Beijing would abide by the MTCR guidelines and thesanctions were subsequently waived in November, 1994.

The institute said Washington is examining any role Beijing might have had in the development of Ghauri missile in violation of MTCR guidelines. Pakistan successfully tested the medium range surface-to-surface missile on April 6, 1998.

The institute said China's aid to Pakistan included tritium to achieve fusion in hydrogen bombs and boost the yield of atomic bombs, heavy water, special industrial furnace which can be used to melt plutonium or enriched uranium into the shape of a nuclear bomb core but also has civilian applications, complete design of a 25 kiloton nuclear bomb, weapons grade uranium to fuel nuclear weapons, a water reactor which had a known connection to the weapons programme, assistance in building the Khushab reactor possibly to produce weapons grade plutonium and the Chashma plutonium reprocessing facility which will begin functioning soon.