The British Government says it is in urgent talks with up to a further 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 British officials are already in contact with up to 10 leading Libyan officials about following 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, British Prime Minister David Cameron said others should now "come to their senses".
Meanwhile, speculation in Tripoli that a series of defections was imminent would not go away. And it was reinforced by the confirmation that Ali Abussalam 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.
Rumours circulating through the Libyan capital focused most closely on Omar Abu Said Dudali, head of the external intelligence service, Mohammed Zwei, the Secretary of the General People's Congress, Deputy Foreign Minister Abdul Ati al-Obeidi, who accompanied Moussa Koussa at least as far as Tunis on the first leg of what turned out to be his flight, and - despite a declaration during the day that he was in his office in Tripoli - the urbane and expert Shokri Ghanem, Oil Minister.
Rebels claimed Dudali had been sent to "liquidate" Koussa but instead joined a group of Libyan officials at Tunisia's Djerba airport who were planning to defect. It was not clear what steps were being taken by the Gaddafi inner circle to prevent such defections.
They are not the first senior figures to be said to be searching for a way out. There had been speculation last month from Washington that Abdullah Senussi, a top security adviser and brother-in-law of Colonel Gaddafi, could have been looking for an exit route from the crisis, either for the country or for himself personally.
The defection of Koussa, who flew into Farnborough Airport in Hampshire aboard a private jet from Tunisia on Thursday, was seized upon by Cameron yesterday as evidence that the Tripoli regime was crumbling.
Speaking at a Downing St press Gaddafi's former spy chief leads defections
conference, 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 give rise to 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 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 Constable 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 St sources suggested Koussa was more likely to be treated as a witness to a renewed investigation.
Educated in America and a fluent English speaker, Koussa played a key role in the rapprochement between Libya and the West after decades of antagonism. 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 also led efforts to secure the release of the only man convicted of the Lockerbie bombing, Abdelbaset al-Megrahi, travelling to Britain to meet Foreign Office and Scottish Government officials in 2008 and 2009.
Meanwhile, despite almost two weeks of Western air strikes, Gaddafi's troops have used superior arms and tactics to push back rebels trying to edge westward along the coast from Benghazi toward the capital Tripoli.
News that United States President Barack Obama had authorised covert operations in Libya raised the prospect of wider support for the rebels.
But Obama's order is likely to alarm countries already concerned that air strikes on infrastructure and troops by the US, Britain and France go beyond a United Nations resolution with the stated aim only of protecting civilians.
US Government sources told Reuters US intelligence operatives were on the ground in Libya before Obama signed the order, to contact opponents of Gaddafi and assess their capabilities. There has been no CIA comment.
"I can't speak to any CIA activities but I will tell you that the President has been quite clear that in terms of the United States military there will be no boots on the ground," US Defence Secretary Robert Gates said.
Inside Gaddafi's heavily fortified compound in the capital Tripoli, crowds of supporters have gathered every night to form a human shield to protect him against the air strikes.
Yesterday, they danced and chanted patriotic songs late into the night as soldiers manning anti-aircraft guns watched the sky over the capital from the back of their pickup trucks.
"We are not afraid, not afraid, not afraid. We will always protect our leader. I want to say to Muammar Gaddafi: I love you so much!" said Zuhra, a teenage girl at the rally.
A Libyan Government spokesman said Gaddafi and all his sons would stay on "until the end".
- AGENCIESBy Donald Macintyre, Cahal Milmo, Oliver Wright