WASHINGTON Pakistan built its first functioning nuclear weapon when the late Prime Minister Benazir Bhutto was in power, says former US Air Force Secretary Thomas Reed.

Reed, a trained weapons designer, made this claim in a book - The Nuclear Express A Political History of the Bomb and Its Proliferation - which he co-authored with Danny Stillman, a former director of the technical intelligence division at America`s Los Alamos National Laboratory.

In an interview to the US News and World Report, published on Friday, Reed argues that China`s assistance to Pakistan was `shocking` but not `short-sighted` as it helped protect China`s interests in the region.

Reed does not explain whether Pakistan`s first functioning nuclear weapon was made during Bhutto`s first or the second tenure.

`We believe that during Bhutto`s term in office, the People`s Republic of China tested Pakistan`s first bomb for her in 1990,` he says `There are numerous reasons why we believe this to be true, including the design of the weapon and information gathered from discussions with Chinese nuclear experts.`

Reed claims that the Pakistanis were so quick to respond to the Indian nuclear tests in 1998 because the Chinese had already prepared them for a response.

`It only took them two weeks and three days,` he notes. `When the Soviet Union took the United States by surprise with a test in 1961, it took the US seventeen days to prepare and test, a device that had been on hand for years.`

According to Reed, the Pakistani response makes it clear that the gadget tested in May 1998 was a carefully engineered device in which they had great confidence.

The Chinese assistance to Pakistan, says Reed, `can be explained by a balance of power India was China`s enemy and Pakistan was India`s enemy.`

Reed claims that the Chinese did a massive training of Pakistani scientists, (just like the Russians had done for them) brought them to China for lectures, even gave them the design of the CHIC-4 device, which was a weapon that was easy to build a model for export.

`There is evidence that Dr. A.Q. Khan used Chinese designs in his nuclear designs,` he writes. `Notes from those lectures later turned up in Libya, for instance. And the Chinese did similar things for the Saudis, North Koreans, and the Algerians.`

The author also argues that sharing nuclear know-how is not unique to China.

`The United States conducted nuclear tests in Nevada openly and with full disclosure in the 1990s on behalf of our UK allies. We speculate on Israeli access to the US test results ... the South Africans also apparently worked with the Israelis on a nuclear test in the South Pacific in 1979.`

In the wake of the Suez crisis in 1956, the French and the Israelis initiated a joint nuclear weapons program that resulted in a test in the Algerian desert. At that test in 1960, two countries went nuclear with one shot, the author notes.

US experts say that China played a major role in the development of Pakistan`s nuclear infrastructure, especially when increasingly stringent export controls in western countries made it difficult for Pakistan to acquire materials and technology elsewhere.

According to a 2001 US Department of Defence report, China has supplied Pakistan with nuclear materials and expertise and has provided critical assistance in the construction of Pakistan`s nuclear facilities.

In the 1990s, China designed and supplied the heavy water Khusab reactor, which plays a key role in Pakistan`s production of plutonium. A subsidiary of the China National Nuclear Corporation also contributed to Pakistan`s efforts to expand its uranium enrichment capabilities by providing 5,000 custom made ring magnets, which are a key component of the bearings that facilitate the high-speed rotation of centrifuges.

According to Anthony Cordesman of the Centre for Strategic International Studies, Washington, China is also reported to have provided Pakistan with the design of one of its warheads, which is relatively sophisticated in design and lighter than US and Soviet designed first generation warheads.

China also provided technical and material support in the completion of the Chasma nuclear power reactor and plutonium reprocessing facility, which was built in the mid 1990s. The project had been initiated as a cooperative program with France, but Pakistan`s failure to sign the NPT and unwillingness to accept IAEA safeguards on its entire nuclear program caused France to terminate assistance.