12:39AM BST 28 Mar 2011
Libyan television confirmed the Gaddafi stronghold had been the target of strikes by "the colonial aggressor", as had Tripoli, and there was a large deployment of troops on the streets of Sirte.
Nato commanders say Libyan regime forces have begun digging in to make a stand in Sirte, raising the prospect that a bloody battle lies ahead as rebel forces barrel westward.
Regime forces who retreated in the face of the rebel advance have begun locating their armour and artillery inside civilian buildings in Sirte, Nato sources said, a tactic designed to make air strikes fraught with risk.
Sirte, which Col Gaddafi repeatedly tried to turn into Libya's capital, is dominated by members of his tribe, the Gaddafi, who remain largely loyal to the regime.
Nato has already targeted the two squadrons of obsolescent Su22 Soviet-era jets housed inside bunkers at the Sirte airbase alongside the civilian airport.
A senior French Nato official told The Daily Telegraph that one strategy could be to starve out the regime forces in Sirte, who do not have the stockpiles of supplies needed to weather a prolonged siege.
Turkish prime minister Recep Tayyip Erdogan suggested Turkey could play a role as a mediator with the Gaddafi regime to secure a ceasefire, warning a prolonged conflict could lead to a "second Iraq" or "another Afghanistan".
Mr Erdogan said Col Gaddafi had to "provide some confidence to Nato forces right now ... to end to the blood being spilled in Libya".
Dr Liam Fox, the Defence Secretary, confirmed that Nato was due to take over command and control of the operation from the Americans, under the leadership of the Canadian Lt Gen Charles Bouchard.
Warning that the Gaddafi regime was continuing to "rain down death and destruction on their own people", Dr Fox said that events on the ground in Libya had persuaded the international community to come together to protect civilians. Libyan military convoys traversing the route from Tripoli have already been choked off by air strikes, and Nato has moved in naval forces to close the option of resupply by sea.
But a prolonged siege could mean real hardship for civilians.
Libyan regime forces have also been focusing on destroying rebel positions in Misurata, the last opposition stronghold in the western Tripolitania region.
Residents said the town, which has been under siege from regime forces for 38 days, was running short of food and water. Eight people were reported dead in a mortar attack by Gaddafi troops last night.
Robert Gates, the US defence secretary, risked increasing the political pressure on President Barack Obama by stating that he did not believe that Libya was a "vital interest" for the United States.
Much of what Mr Gates said will only increase criticism on the eve of Mr Obama's live prime-time television address to America on Monday night.