Britain and its Nato allies are making plans to send warplanes in to Libya and arm rebels as Western determination hardens to force out Colonel Muammar Gaddafi and prevent a humanitarian disaster.

Going further than any world leader, David Cameron said yesterday that he had ordered General Sir David Richards, the Chief of the Defence Staff, to work on how to impose a no-fly zone in Libyan airspace. Fighter jets would shoot down any encroaching Libyan aircraft to stop Colonel Gaddafi from bombing his own people.

Mr Cameron insisted that further violence would not be tolerated and did not rule out the possibility of Nato sending ground troops. “It is clear that this is an illegitimate regime that has lost the consent of its people.