DAFNIYA, Libya - Libyan rebel fighters based in Misrata advanced about 20 km (12 miles) west towards the capital, rebel commanders said on Wednesday, but government forces were shelling their positions. Rebel commanders in Dafniya, on the western outskirts of Misrata, told Reuters their forces had made the advance overnight along one stretch of the front line, but Reuters journalists were unable to confirm that independently. The advance – which would be the biggest by the rebels in weeks of largely static fighting west of Misrata – could leave the rebels exposed because they have not had time to dig in and build defensive positions. From a field hospital in Dafniya, the sound of the impact from mortars, artillery and Russian-made Grad rockets could be heard every few seconds. A Reuters reporter at the hospital saw two wounded soldiers being brought in from the front. One was injured in the upper thigh and another had leg wounds. Medical staff bandaged them up for transport to another hospital in the centre of Misrata, which is 200 km (130 miles) east of Tripoli. The stretchers on which they were brought in were quickly washed down and sent back to the front line. One rebel fighter said one of his colleagues had been killed in the artillery bombardment on Wednesday.