Large protests have continued overnight in Libya following Thursday's "Day of Rage" against the government.
Thousands came out on to the streets of the eastern city of Benghazi and activists also set up camps in al-Bayda, eyewitnesses said.
Confrontations between security forces and protesters left two dozen people dead and many wounded on Thursday, according to Human Rights Watch.
This week's protests are the first in Libya, where dissent is rarely allowed.
The BBC's Jon Leyne in Cairo says violent confrontations are reported to have spread to five cities in demonstrations so far, but not yet to Tripoli, the capital, in any large numbers.
Our correspondent says the reports reflect an extremely tough government response, including the use of gunfire and even denying supplies to hospitals.
Funerals of some of those killed are expected to be held on Friday in Benghazi and al-Bayda, which correspondents say could spur more protests.
Human Rights Watch says 24 people have been killed and many wounded in the demonstrations which continued into the night on Thursday.
Eyewitnesses believe the death toll could be even higher, our correspondent says.
Pro-democracy protests have recently swept through several Arab nations, with the presidents of Tunisia and Egypt forced from power amid growing unrest.
'Defend the revolution'
Activists supporting Libya's government have also been out on the streets in Tripoli. They shouted slogans in support of Libya's leader, Muammar Gaddafi.
On Thursday, the demonstrators in Green Square shouted: "We are defending Gaddafi and the revolution!" and "The revolution continues!" Others hurled insults at foreign media.
Col Gaddafi briefly visited the square early on Friday, according to images aired by state TV, AFP news agency reports.
Activists used social networking websites such as Facebook and Twitter to call for the "Day of Rage".
One witness, a woman in Benghazi who joined the protests on Thursday, told the BBC she saw hundreds of people taking part in the demonstrations.
She saw police firing their guns and she said they were not just firing into the air, but firing at people as well.
Col Gaddafi is the Arab world's longest-serving leader, having ruled oil-rich Libya since a coup in 1969.
The Middle East has recently seen a wave of protests fuelled by discontent over unemployment, rising living costs, corruption and autocratic leaderships.
This began with the overthrow of Tunisia's leader, Zine al-Abidine Ben Ali, in January. Protests in Egypt then lead to the resignation of President Hosni Mubarak.
In recent days there have also been anti-government demonstrations in Yemen, Bahrain, and Iran.