British Tornado aircraft have fired precision-guided missiles against a large headquarters bunker in Colonel Muammar Gaddafi's home town of Sirte as intense fighting continued on the ground in Libya.
The latest Nato action overnight came as Defence Secretary Liam Fox urged the Gaddafi regime to recognise that the "game is up" and called for it to stop attacking its own people.
The whereabouts of the Libyan dictator remained unknown despite the involvement of Nato intelligence and reconnaissance assets.
Dr Fox told Sky News it was "premature to assume" the fighting was over as strong pockets of resistance remained.
Nato and UK forces from RAF Marham launched an attack on a command and control bunker of the Gaddafi regime in Sirte.
Despite the ongoing violence and the failure to capture Gaddafi, the National Transitional Council (NTC) cabinet was pressing ahead with its hugely symbolic move from eastern stronghold Benghazi to Tripoli.
Dr Fox said: "It's still important that we remove the potential for the regime to counter-attack against the NTC and to continue to wage war on their people, but it is far too early yet to say what the security situation will be in the weeks ahead."
He added: "We have information that there are some elements of the regime in Sirte. Where they are still continuing to wage war on the people of Libya, we will continue to degrade their military capabilities.
"The regime needs to recognise that the game is up. It is all over and they need to stop attacking their own people.
"But as long as they do continue to attack the people, Nato will continue to act as we have done under the UN Resolution 1973 to degrade the command and control and the military assets that they are using against the people of Libya."