Rebel-held areas in Libya

Rebels quickly seized control of many towns in the east of the country as protests swept across Libya in February, but have since found themselves losing their grip on many of them.

This part of the country has traditionally been opposed to Col Gaddafi's rule, and large elements of the military switched to the rebel side. But Col Gaddafi's army have far greater resources, including an airforce, and have pushed the rebels back.

On Saturday, 19 March, forces loyal to Col Gaddafi began attacking Benghazi, the main rebel base and a city of more than 670,000 people.

With the battle for Benghazi under way, only the towns to east of it - including Bayda, Derna and Tobruk, near the border with Egypt - remain under rebel control. However, if Benghazi were to fall, these would appear defenceless.