Libyan leader Colonel Muammar Gaddafi has made a "historic" decision to scrap his country's programmes to develop weapons of mass destruction and to allow international inspectors to verify and oversee the process.
Downing Street said last night that Libya had been close to developing a nuclear device.
In a surprise revelation that was quickly followed by a similar announcement by President George Bush in Washington, Tony Blair said that nine months of intensive negotiations between Britain, the United States and Libya had resulted in Colonel Gaddafi's decision to abandon all efforts to develop any chemical, biological and nuclear weapons.
"Libya has now declared its intention to dismantle these weapons of mass destruction completely and to limit the range of Libyan missiles to no greater than 300km," the Prime Minister said, speaking in Durham. He said Libya had confirmed it wanted the process of putting the weapons out of use to be "transparent and verifiable".
He added: "Libya came to us in March following successful negotiations on Lockerbie to see if it could resolve its WMD issue in a similarly co-operative manner. Nine months of work followed with experts from the US and UK, during which the Libyans discussed their programmes with us." In Washington President Bush said: "With today's announcement by its leader, Libya has begun the process of rejoining the community of nations. And Colonel Gaddafi knows the way forward. Libya should carry out the commitments announced today."
It is far from clear precisely what WMD if any Tripoli may actually possess and the task of verification will fall to the International Atomic Energy Agency (IAEA) and the Organisation for the Prohibition of Chemical Weapons.
Downing Street said that weapons experts had visited Libya in October and again earlier this month and had been shown "nuclear, chemical, biological and missile-related activities".
A statement said: "During the three weeks of visits, our experts were shown covert facilities and equipment and given information on Libya's efforts to develop WMD over many years."
But US intelligence reports suggest that while Libya has been trying to develop WMD, it may have not have actually produced effective, deliverable weapons. Downing Street said Colonel Gaddafi had not "acquired a nuclear weapons capability, though it was close to developing one".
The decision by Libya was last night hailed by both London and Washington as a victory in the so-called war on terror and that the invasion of Iraq had sent a clear message to any other nations seeking to develop WMD.
But while last night's announcement came as a surprise, Libya has been making strenuous efforts in recent years to lose its status as a "rogue nation" and to return to the international fold in order to restart trading with the US after 17 years of sanctions.
Before relations between the North African country and the West soured utterly in the 1980s, a number of Western oil companies operated in Libya.
There was also a suspicion that last night's announcements were stage-managed to divert attention from the failure of the US and Britain to discover any WMD in Iraq - the purported reason for the invasion. The US revealed this week that it was in effect giving up the search for such weapons in Iraq.
Libya's willingness to give up its WMD programme is essentially another step in the process that was started earlier this summer when it agreed to accept responsibility for the Lockerbie bombing and to pay $10m (£5.6m) in compensation to the relatives of each of the 270 people killed in the 1988 attack on the airliner.
Libya has been making efforts to return to the international fold and develop closer trade links with the West since 1999, when it handed over two Libyan suspects to stand trial under Scottish law at a purpose-built court in the Netherlands. In January 2001, one of those suspects, Abdel Basset al-Megrahi, was convicted. His co-accused was cleared.
In exchange for the compensation and the acceptance of responsibility, the United Nations in September formally lifted sanctions against Libya that had been in place since 1991. America's own sanctions have remained, with Washington insisting they would stay in place until Libya proved it "changed its ways". The UN resolution also demanded that Libya give up any WMD.
Mr Blair said Libya's decision represented a "victory for diplomacy". He said: "This courageous decision by Colonel Gaddafi is an historic one. I applaud it. It will make the region and the world more secure. It shows that problems of proliferation can, with good will, be tackled through discussion and engagement, to be followed up by the responsible international agencies."
He went on: "Libya's actions entitle it to rejoin the international community. I have spoken to Colonel Gaddafi to say that, as the process of dismantlement goes forward, I now look forward to developing a productive relationship with him and with Libya."
At the White House, Mr Bush said the war in Iraq and efforts to stop North Korea's nuclear programme had sent a clear message to countries such as Libya that they must abandon weapons programmes. "In word and in action, we have clarified the choices left to potential adversaries," he said in a televised speech. In Tripoli, the Libyan Foreign Ministry issued a statement that said Libya "had decided on its free will to ... completely eliminate the internationally banned weapons of mass destruction". It said the agreement was reached after meetings with "experts" from Britain and the United States.Reuse content