They are just a small part of the security and surveillance entourage that surround Doctor Abdul Qadeer Khan and his every movement, and the house is one of several palatial villas he owns in the capital.

A.Q. Khan, credited with fathering Pakistan's nuclear bomb, is publicly hailed as a national hero. Born in 1936 in Bhopal, India, he was 10 years old when his family migrated by train to Pakistan during the bloody 1947 partition of the sub-continent.

But enemies deride him as little more than a metallurgist who stole data.

"He's a metallurgist, not a nuclear scientist as widely advertised ... he has certainly not made any outstanding inventions," said Pervez Hoodbhoy, professor of physics at Islamabad's Quaid-e-Azam University.

Khan's contribution to Pakistan's nuclear programme was the procurement of a blueprint for uranium centrifuges, which transform uranium into weapons-grade fuel for nuclear fissile material.

He was charged with stealing it from The Netherlands while working for Anglo-Dutch-German nuclear engineering consortium Urenco and bringing it back to Pakistan in 1976.

On his return, he was put in charge of Pakistan's uranium enrichment project.

By 1978 his team had enriched uranium and by 1984 they were ready to explode a nuclear device, he told Pakistan's The News daily in a 1998 interview.

The project is credited with ultimately leading to Pakistan's first nuclear test explosion in May 1998.

In 1981 the Engineering Research Laboratories was renamed A.Q. Khan Research Laboratories (KRL) in his honour.

Khan's golden aura began to dim in March 2001 when President Pervez Musharraf, reportedly under US pressure, removed him from the chairmanship of KRL and made him special advisor on strategic and KRL affairs.

Now the father of the first nuclear bomb in the Islamic world is at the centre of allegations about the proliferation of nuclear know-how to a rogues' gallery of states: North Korea, Iran and Libya.

"If the international community had a proliferation most-wanted list, A.Q. Khan would be the 'most-wanted' on the list," Robert Einhorn, assistant secretary of state for non-proliferation under former US president Bill Clinton, was quoted saying in The News in January 2003.

Pakistan's nuclear establishment was stunned to see its most revered hero subject to questioning in December after Islamabad was sent a letter from the International Atomic Energy Agency, a UN watchdog, which raised claims that Pakistani scientists were the source of sold-off nuclear knowledge.

Khan was the only one of 13 nuclear scientists, engineers and administrators who have since been questioned who was not taken into custody.

The government has said it was probing whether individuals sold nuclear technology, namely the uranium centrifuge designs, for personal profit.

Hoodbhoy believed the accusations, while yet to be publicly proved, were plausible.

"He's a man who does things for profit. He operates in a milieu where the sharing of such things is not regarded badly," Hoodbhoy told AFP.

Khan and his KRL associates may have traded nuclear information with foreign brokers based in Dubai, an official familiar with KRL said.

"Khan and the group was mostly responsible for bringing resources for Pakistan's nuclear programme from outside, particularly through a Dubai-based group of international brokers," the official told AFP, requesting anonymity.

"While they were dealing with these brokers, the suspicion is that they may have passed on nuclear know-how to these brokers, who then passed it on Iran and Libya."

Khan himself said in a speech to the Pakistan Institute of National Affairs in 1990 that he had shopped around on world markets while developing Pakistan's nuclear programme.

"It was not possible for us to make each and every piece of equipment within the country," he said.

"We devised a strategy by which we would go and buy everything we needed in the open market."

After the May 1998 tests resulted in international sanctions, the sense of anti-Western nationalism among Pakistan's nuclear establishment and the Pakistan Atomic Energy Commission (PAEC) grew, Hoodbhoy said.

"People in PAEC were saying, 'If the US imposes sanctions, and the economy collapses, why not sell our bomb and prevent economic collapse?'"

Hoodbhoy described the atmosphere at KRL as "very religiously charged."

"They have, especially over the last decade or so, become much more religious and their attitudes are considerably more anti-Western than 30 years ago."

Khan believed in nuclear defence as the best deterrence. Talking to The News after the 1998 tests, Khan said Pakistan "never wanted to make nuclear weapons. It was forced to do so."

Hoodbhoy said he espoused Islamic nationalism.

"He thinks the bomb is essential to protect Islam against assault from those who hate Islam," Hoodbhoy said.

WAR.WIRE