The British Government said it was in urgent talks with up to another 10 senior figures in Colonel Gaddafi's creaking regime about possible defection following the dramatic arrival in Britain of the Libyan dictator's chief henchman for much of his 40 years in power.
As former foreign minister Moussa Koussa was reported to be "talking voluntarily" to British officials yesterday, the Libyan regime was desperately struggling to limit the damage of the stunning desertion, suggesting he was exhausted and suffering from mental problems.
But its capacity to stop the domino effect appeared to be limited. The Independent understands that British officials are already in contact with up to 10 leading Libyan officials about following Mr Koussa's lead and deserting Gaddafi. As Libyan diplomats at the United Nations said they expected further defections and reports emerged that a senior figure in the country's London embassy had changed sides, David Cameron said others should now "come to their senses". Meanwhile, speculation was rife in Tripoli that a series of defections was imminent. And it was reinforced by the confirmation that Ali Abdussalam Treki, a top Libyan official who had also served as Foreign Minister and UN ambassador, had quit over the "spilling of blood" by government forces.
But despite official denials, unverified rumours circulating in Tripoli, fuelled by an Al Jazeera report, focused most closely on Abuzed Omar Durda, head of the external intelligence service, Mohammed Zwei, the Secretary of the General People's Congress, and Deputy Foreign Minister Abdulati Al Obeidi, who accompanied Moussa Koussa at least as far as Tunis on the first leg of what turned out to be the Foreign Minister's flight to the UK. A fourth official, the urbane Shokri Ghanem, Oil minister, denied he had fled and told Reuters he was in his office in Tripoli.
Rebels claimed that Mr Durda had been sent to "liquidate" Mr Koussa but instead joined a group of Libyan officials at Tunisia's Djerba airport who were planning to defect.
There had been speculation last month from Washington that Abdullah Senussi, a top security adviser and brother-in-law of Colonel Gaddafi's, could have been looking for an exit route from the crisis, either for the country or for himself personally. But there was no evidence last night that he had deserted, or intended to do so.
It is also understood that British officials have spoken to Mohammed Ismail, a senior aide to Gaddafi's son Saif al-Islam, who visited London recently. The contact was part of the concerted attempt by the Foreign Office to reach out to members of the Gaddafi regime to encourage them to defect or at least disassociate themselves from the regime.
Last night, British government sources played down the significance of the contact with Mr Ismail but confirmed that there were ongoing discussions with a number of Libyan contacts – which were built up around the time of Britain's rapprochement with Libya – in an attempt to build on Moussa Koussa's defection. "This is very much part of business as usual," one source said.
The defection of Mr Koussa, who flew into Farnborough airport in Hampshire aboard a private jet from Tunisia on Wednesday night, was seized upon by David Cameron as evidence that the Tripoli regime was crumbling.
Speaking at a Downing Street press conference, Mr Cameron said: "The decision by the former Libyan minister to come to London to resign his position is a decision by someone at the very top. It tells a compelling story of the desperation and the fear right at the very top of the crumbling and rotten Gaddafi regime."
But while British officials were eager to capitalise on the strategic significance of the 62-year-old former Libyan spy chief's vow that he was "no longer willing" to represent Gaddafi on the international stage, it was made clear his arrival will also raise uncomfortable questions about atrocities including the Lockerbie bombing, which happened when he was a senior figure in Libya's foreign intelligence service.
Scottish prosecutors told the Foreign Office they want to interview Mr Koussa in relation to the destruction of Pan Am flight 103 with the loss of 270 lives. He could also face questioning about the murder of PC Yvonne Fletcher outside the Libyan embassy in 1984.
Foreign Secretary William Hague said his Libyan counterpart had not been offered immunity against prosecution in return for his defection. But privately, Downing Street sources suggested Mr Koussa was more likely to be treated as a witness. It is believed he is now being held at Farnham Castle in Surrey, a conference centre, wedding venue and tourist attraction.
Educated in the US and a fluent English speaker, Mr Koussa played a key role in the rapprochement between Libya and the West. The spy chief negotiated a multibillion-pound compensation package for the victims of Lockerbie and other atrocities as well as ending its "weapons of mass destruction" programme. He led efforts to secure the release of the only man convicted of the Lockerbie bombing, Abdelbaset al-Megrahi.
The priority for the coming days will be to debrief Mr Koussa on the state of the Gaddafi regime, in particular what military capabilities it still possesses and the identification of other defectors, possibly with his co-operation as an intermediary.
Amid concerns about Mr Koussa's mental state, officials have been careful to surround him with familiar figures, including the ambassador to Tripoli, Richard Northern, who is now back in Britain following the closure of the British embassy. Libyan opposition figures made clear they have little sympathy for the high-profile refugee. Mustafa Gheriani, a spokesman for the Libyan rebel government, said Mr Koussa was implicated in the assassination of opposition figures in exile and brutal internal repression.
He said: "This guy has so much blood on his hands. There are documented killings, torturing. There's documentation of what Moussa Koussa has done. We want him tried by Libyan people."
The response in Tripoli, meanwhile, did not initially suggest much knowledge of the factors leading to Mr Koussa's exit. Moussa Ibrahim, the regime's spokesman, told reporters that the Foreign Minister had had health problems, including diabetes and high blood pressure, and that he had been given permission to leave the country for medical treatment. He said later he had been expected to have political discussions while in Tunisia but had not mentioned going to the UK. Nor had he been in touch with officials in Tripoli since his departure. "We understand that he has resigned from his position," he said.
Meanwhile, buoyed by news of covert US support on the ground, rebels began massing on the edge of Brega, preparing for a counter-attack on the town they lost on Wednesday. The rebels had withdrawn rapidly after coming under rocket fire from Gaddafi's forces.
The other defectors – and those who may follow
Defected: Mustafa Mohamed Abud al-Jeleil
Libya's former justice minister resigned on 21 February over the regime's "excessive use of violence against protesters". He later alleged Colonel Gaddafi personally ordered the Lockerbie bombing.
Defected: Ali Abussalam Treki
The senior Libyan politician reportedly defected yesterday after decades of service to Gaddafi's regime, including stints as foreign minister and United Nations representative.
May be next: Adbdullah Senussi
The whereabouts of Colonel Gaddafi's brother-in-law – who is also his top security adviser – were unknown yesterday, leading to speculation that he could have joined the ranks of defectors.
May be next: Shukri Ghanem
Libyan opposition television reported that Libya's Oil Minister was one of four officials waiting at Tunisia's Djerba airport on Wednesday in the hope of joining Moussa Koussa in London.
May be next: Abuzed Omar Durda
On hearing of Moussa Koussa's defection Gaddafi ordered the head of Tripoli's foreign security agency, Mr Durda, to "liquidate" him, according to sources. Mr Durda was later reported to be one of the officials at Djerba airport.