David Cameron has reacted to the Libyan government's offer of a ceasefire by saying he would judge Col Muammar Gaddafi "by his actions not his words".
The UK prime minister has said UK warplanes are being deployed to help protect the Libyan people from "brutal" attacks by the Gaddafi regime.
A joint UK, US and French operation is to be launched after the UN backed a resolution authorising a no-fly zone.
In response, the Libyan regime said it was calling an immediate ceasefire.
Libyan foreign minister Mussa Kussa said the country would abide by the UN resolution, which calls for an immediate ceasefire and an end to attacks on civilians, to stop "all military operations" and was prepared to allow UN observers into the country to verify its compliance.