Libyan rebels and pro-Gadafy forces exchanged heavy artillery fire near the western city of Zlitan today as the rebels tried to push deeper into government-held territory east of the capital.
Warplanes could be heard in the skies above, although it was unclear whether there had been air strikes.
Zlitan, just 160km from Tripoli, is the next major town on the Mediterranean coast road to the capital. Capturing it would be a major victory for the rebels.
In Misrata, rebel spokesman Ahmed Hassan said 10 civilians had been killed and another 40 wounded when Gadafy forces shelled the city. The report could not be immediately verified.
The exchanges were the heaviest in the area since since last week, when 31 rebels were killed. At a field hospital in Dafniyah, ambulances arrived with at least five seriously wounded rebel fighters.
The rebels have said they will not attack Zlitan because of tribal sensitivities, but are recruiting fighters from the town and waiting for the residents to rise against Muammar Gadafy.
Nato planes resumed bombardments of Tripoli today with six loud explosions ringing out in the south of the city. The daytime strikes, which hit the capital before noon, sent columns of thick black smoke into the sky.
A few hundred people filled the capital's Green Square waving green revolutionary flags and chanting pro-Gadafy slogans following Friday prayers.
The rebellion began four months ago to the day in the eastern city of Benghazi. Nato intervention has been going on for nearly 13 weeks, longer than many of its backers expected, and strains are beginning to show within the alliance.
Rebel advances towards Tripoli have been slow, while weeks of Nato strikes pounding Gadafy's compound and other targets have failed to end his 41-year-old rule.
Rebel forces are now fighting Col Gadafy's troops on three fronts: in the east of the country around the oil town of Brega, on the road to Tripoli from the rebel-held port of Misrata, and in the Western Mountains southwest of Tripoli.
Meanwhile, Russia's envoy to Libya said today that representatives of Col Gadafy's government are in contact across Europe with members of the Libyan rebellion.
Mikhail Margelov, the Kremlin’s special representative for Africa, met Libyan prime minister Al Baghdadi Ali Al-Mahmoudi in Tripoli yesterday as part of Moscow's efforts to help end the conflict, which entered its fourth month toda.
Speaking to reporters in Tunis today, Mr Margelov said the prime minister had told him that representatives from his government were in contact with officials from Benghazi in several European countries, including France, Germany and Norway.
"The prime minister wanted to tell me that they have a sort of communication channel with the Transitional National Council," Mr Margelov said.
The rebels have said they will not negotiate with Tripoli until Col Gadafy and his sons step down.
Col Gadafy's son said yesterday his father was willing to hold elections and step aside if he lost, an offer rejected by rebels and the United States.
Saif al-Islam told an Italian newspaper that the elections could be held within three months and transparency could be guaranteed through international observers. He said his father would be ready to cede power if he lost the election, though he would not go into exile.
The rebel leadership in the eastern stronghold of Benghazi rejected Col Gadafy's son's election offer.
"We tell him [Saif al-Islam] that the time has passed because our rebels are at the outskirts of Tripoli, and they will join our people and rebels there to uproot the symbol of corruption and tyranny in Libya," rebel spokesman Abdel Hafiz Ghoga told Al Jazeera television.
A US State Department official also dismissed the election idea, saying it was "a little late for that".