Forces loyal to Libyan leader Muammar Gaddafi have begun using tanks and artillery to fight rebels, who say they lack weapons to fight the army.
Fighting between rebels and pro-Gaddafi forces for control of many eastern parts of the country has entered its third week.
"Our weapons cannot repel tanks and artillery," the rebel Shuruk website said.
Government troops shelled the rebel-held city of Zawiya on Wednesday, with reports of considerable casualties among the rebels. Al Jazeera also reported further air strikes on the rebel-held oil port of Ras Lanuf.
Thousands of people have been killed since the first protesters began demanding the end of Gaddafi's 41-year rule in mid-February.
The rebels are stepping up calls for the UN to impose a no-fly zone over Libyan airspace. A UN resolution on the issue is to be debated by NATO defense ministers later this week. Russia has said it is against all military intervention.
In an interview with Turkish TV, Gaddafi described the no-fly zone as a "colonialist plot" by the West to take control of Libyan oil.
MOSCOW, March 9 (RIA Novosti)
