Fighting has resumed in the western Libyan city of Zawiya between rebels and forces loyal to Libyan leader Muammar Gaddafi.
The town was seized by rebels in March, but government forces recaptured it in less than two weeks of heavy fighting.
The port city, about 30km (18 miles) west of Tripoli, is the site of an important oil terminal.
Col Gaddafi's forces are also struggling against rebels in other western towns and cities.
Fighting shook Misrata where doctors told the Associated Press that six people had been killed and 16 wounded in shelling on Sunday.
Meanwhile, Libyan state television on Sunday showed pictures of Col Gaddafi, playing chess with the president of the international chess federation.
Correspondents say this is taken as an indication that the Libyan leader has no intention of leaving power.
Government forces in Misrata have the rebels surrounded on three sides, but the port remains open to resupply the anti-government forces.
There were also clashes on farmland between Misrata and the neighbouring town of Zlitan, AP reports, as well as battles in Yafran.
Col Gaddafi's forces pounded the outskirts of Zintan on Sunday, killing at least seven rebels, according to Agence France-Presse.
In Zawiya, fighting partially closed the main road and supply route from Tripoli to the Tunisian border.
According to Reuters, one rebel spokesman in the city said that pro-government forces had positioned snipers on the tops of buildings and that 13 people had died in clashes on Saturday.
With Nato increasing its bombing attacks on Col Gaddafi's troops, rebel forces appear to be gaining momentum, says the BBC's Wyre Davies in Tripoli.
Nato now says it has carried out more than 4,000 air strikes on Libyan government forces.
The renewed fighting in Zawiya means government commanders are faced with the problem of where to position their troops and tanks.
Moving heavy weapons risks bringing down Nato air strikes, says our correspondent.