Over two decades, Libya secretly produced weapons grade nuclear material in a programme to make an atomic bomb that was more extensive than previously believed, the UN nuclear watchdog said in a report on Friday.
The International Atomic Energy Agency (IAEA) report outlines how Libya relied on an intricate network of illicit atomic suppliers who skirted international sanctions to sell sensitive technology to states like Libya, Iran and North Korea.
The report, authored by IAEA chief Mohamed ElBaradei, showed Libya's nuclear programme began as far back as the early 1980s.
The agency said Libya failed to declare a number of highly sensitive experiments linked to weapons production, including "the separation of a small amount of plutonium", albeit "in very small quantities".
"The key thing here is the know-how, not the amount," said one Western diplomat who follows the agency's work.
Plutonium and highly enriched uranium are two substances that can be used to form the core of a nuclear bomb.
The IAEA usually defines a "significant" amount of plutonium as the amount needed to build a nuclear weapon - 10 kg (22 pounds) - so the "small amount" would have been considerably less than that, most likely a matter of grams.
"This is very serious," David Albright, a former UN weapons inspector and head of the Institute for Science and International Security (ISIS), said of the report.
"Whether they'd have finished (building a weapon) in a year or five years, they'd have finished. Thank God Libya decided to give that up," he told Reuters of the programme.
In December, Libya said it was scrapping its nuclear, biological and chemical weapons programmes and invited US, British and international experts to help it disarm.
Jon Wolfsthal, deputy director of the non-proliferation Project at the Carnegie Endowment for International Peace, said the most disturbing element of the report is how much went on in Libya for so long before anyone seemed to know about it.
"It is a disturbing sign that Libya was able to accumulate materials and technology without the IAEA or apparently US intelligence being aware of these developments," he told Reuters.
"It is especially disturbing that Libya was able to use safeguarded facilities without detection by the IAEA."
ElBaradei, who is also preparing a similar report on Iran for the March 8 IAEA board meeting, will travel to Libya next week to meet senior officials and review progress in the dismantling of its nuclear weapons programme.
In addition to ordering 10,000 advanced uranium enrichment centrifuges capable of producing large amounts of bomb-grade uranium, one of the most sensitive items obtained by Libya were designs for a nuclear weapon.
The IAEA said that by hiding its activities Libya had breached its obligations under the non-proliferation Treaty (NPT).
One Western diplomat said the verdict may prompt the IAEA governing board to report Libya to the UN Security Council.
However, he said the IAEA would not ask the Council to consider sanctions over the breach because it had praised Tripoli's coming clean about its nuclear past.
Albright said the report indicated the IAEA may need to know more about the massive nuclear black market and the companies that supplied it in order to stamp it out completely.
The IAEA report said: "It is evident already that a network has existed whereby actual technological know-how originates from one source, while the delivery of equipment and some of the materials have taken place through intermediaries."
In some cases, Libya got technology from suppliers who had no idea who the real end user was. But the IAEA said that in other cases the suppliers clearly knew "since the identity of equipment such as serial numbers had been removed".