Pakistan's Abdul Qadeer Khan, revered as a hero in Pakistan for founding the country's nuclear programme, begged forgiveness in an extraordinary broadcast televised in Pakistan Wednesday where he admitted leaking nuclear secrets abroad.

Investigators earlier said Khan had shared sensitive nuclear technology with Iran, Libya and North Korea for more than a decade.

ElBaradei, the head of the UN's International Atomic Energy Agency, told reporters at IAEA headquarters in Vienna: "Dr. Khan is the tip of an iceberg for us."

Khan "was not working alone," said ElBaradei, speaking on the sidelines of a conference on nuclear non-proliferation.

"We need to follow this through. We need to know who was producing centrifuges" that can be used to make highly enriched uranium for atomic bombs.

"We have to make sure it will not be repeated," ElBaradei said about the clandestine nuclear dealing.

He said Pakistan has been "quite cooperative so far" with the IAEA, the UN's agency for guaranteeing nuclear non-proliferation worldwide, in trying to piece together what ElBaradei called "a supermarket" of international smuggling of nuclear materials and information such as weapons blueprints the United States has found in Libya.

"We're looking into who else got the materials, other than Libya or Iran," ElBaradei said.

He said individuals in at least five countries were involved in trafficking that went back at least to the 1980's.

Khan "was an important part of the process. Now he's cooperating with Pakistani authorities so hopefully we'll get as much information as we need," the UN official said.

Analysts in Pakistan have said it was hard to see how Khan could have acted without the knowledge of higher authorities, although both Khan and the Pakistani government deny this.

Pakistani authorities said Thursday they had issued formal arrest orders on five scientists and administrators, including several colleagues of Khan, who had already been detained in connection with the probe.

ElBaradei said the clandestine process involved "items that were manufactured in other countries. There were items that were assembled in different countries.

"There was diverting on ships," ElBaradei said.

He said the IAEA "needs to follow through and know who was producing the centrifuges, who was producing different parts."

"A lot of bits and pieces had been produced in different countries," ElBaradei said, adding that the case of Dr. Khan "raises more questions than it answers."

"What increases my anxiety is the ability of many countries now to produce equipment and materials that can lead to a nuclear weapons program," ElBaradei said.

He said export control was now "the most important issue" in preventing nuclear proliferation.

Nuclear technology exports are currently overseen by an informal international group called the Nuclear Suppliers Group (NSG).

ElBaradei said the time had come "to have a system of export controls that insure that companies in different countries are controlled... We need an overall system of export control."

In the Malaysian capital Kuala Lumpur meanwhile, a top police official said his services were investigating a company controlled by a son of Prime Minister Abdullah Ahmad Badawi over allegations that it was involved in supplying parts for Libya's nuclear weapons programme.

ElBaradei also said that the IAEA needed more intelligence help from countries like the United States.

"Sometimes information came to us that was not very timely," he said, referring to an agreement the United States and Britain reached with Libya for Tripoli to give up its weapons of mass destruction programs.

ElBaradei said the IAEA didn't know about it "until Libya announced it," in December, after months of secret talks with Washington and London.

But the IAEA has since overseen the removal of sensitive equipment from Libya and ElBaradei said this technology, including weapons blueprints, was under IAEA seals in the United States.

He said an IAEA team was now in the United States to remove the seals and that the Americans would have full access to the equipment and technology.

WAR.WIRE