Misurata early Tuesday came under an artillery attack by Libyan forces in an attempt to advance toward the northwest city in an effort to recapture parts under control by rebels.
Twenty government soldiers were captured in the clashes.
Separately, Libyan officials are claiming to have intercepted two boats carrying a cache of weapons from Qatar, reportedly intended for rebels fighting forces loyal to Muammar Gaddafi, Arab-language satellite news channel Al-Jazeera reported on Tuesday.
Government spokesman Moussa Ibrahim said 11 rebels on Monday were captured from the boats close to shore near the town of Janzour, west of Tripoli.
"In the early hours of this morning around 4 o'clock our security forces intercepted the submission of many weapons from a ship that raises the Tunisian flag to two small Libyan boats with some Libyan rebels on board the boats," he said, according to Al-Jazeera.