A network of Libyan defectors, including the former regime stalwart Moussa Koussa, are helping Nato to destroy Muammar Gaddafi's military sites, including bunker complexes from which much of the war has been run, according to senior officials in Libya.
Nato planners have stepped up their operations over the capital, Tripoli, and the western mountains in recent days, despite a strike on the eastern city of Brega early on Friday that killed up to 11 people, many of them Islamic clerics.
But British defence chiefs are applying pressure on other Nato countries to escalate the bombing campaign against Gaddafi amid deepening concerns that military action will end in stalemate.
Nearly two months since the start of air strikes, they fear divisions within Nato and at the UN will lead to fewer sorties just at a time when, they claim, the regime is starting to feel the pinch and even its core support showing signs of cracking.
Despite almost nightly air strikes, and increasing numbers of daylight attacks on the outskirts of Tripoli, the capital remains under regime control. The city is free of checkpoints and any opposition elements are maintaining a low profile. Discontent – for now – seems directed at France, Britain and Italy, whom residents blame for a critical fuel shortage.
But there is growing anger towards former regime loyalists, first among them Koussa, who defected to Britain in early April after more than 30 years as Gaddafi's most trusted henchman.
The former foreign minister and intelligence chief is understood to have passed on "invaluable" details of the dictator's police state, including the precise location of the regime's most sensitive sites.
"He was the 'black box' of the regime," said an unnamed official who worked with Koussa. "I was with him the day before he left and nobody knew that he was going to do that. Why did he do it? I'd say he must have been emotionally weak. Things must have got to him."
After spending a month in Britain, Koussa is now in Qatar, from where he is believed to be helping Nato map targets.
Publicly, the regime has vehemently attacked Nato for bombing sites it variously describe as either "civilian, or non-military". Libyan government spokesman, Moussa Ibrahim, described as "murderous and barbaric" the strike on the Brega guest house which killed the Imams.
But on Saturday a Dutch engineer, Freek Landmeter, claimed he had built a large bunker for the Gaddafi regime underneath the site in 1988. Landmeter provided GPS co-ordinates for the project which matched those provided by the regime on Friday for the guest house.
Another bunker site was bombed inside Gaddafi's Bab al-Aziziyah compound in Tripoli. A merry-go-round had been put 150 metres from a main entrance point and families had been invited to camp nearby as a show of support for the regime.
Nato described the Brega and Tripoli sites as "command and control centres'.
British military planners had urged Nato to re-prioritise its targets in Libya to include static sites, such as command and control centres, and not only those posing a direct and clear threat to Libyan civilians, such as tanks and artillery.
Well-placed UK government officials made this plain on Sunday as General Sir David Richards, chief of the defence staff, said he wanted the rules of engagement changed so attacks can be launched against the infrastructure propping up Gaddafi.
"The vice is closing on Gaddafi, but we need to increase the pressure further through more intense military action," Richards told the Sunday Telegraph.
"We now have to tighten the vice to demonstrate to Gaddafi that the game is up and he must go", he added. "We need to do more", Richards said. "If we do not up the ante now there is a risk that the conflict could result in Gaddafi clinging to power." Richards continued: "At present Nato is not attacking infrastructure targets in Libya. But if we want to increase the pressure on Gaddafi's regime then we need to give serious consideration to increasing the range of targets we can hit."
Liam Fox, the defence secretary, said on Sunday that a number of Nato countries were "less happy" with Britain's decision to extend the number of targets, to include command and control centres and what he called "intelligence networks".
Speaking on BBC1's Politics Show, he said: "Not all Nato countries take the same view." Fox added that if Gaddafi regime commanders chose to be in a command and control centre it was "a risk they take".
