Libyan protesters defied a crackdown and took to the streets in four cities yesterday on what activists have dubbed a "day of rage".
At least 20 demonstrators have been killed in clashes with pro-government groups, according to reports, and Human Rights Watch said Libyan internal security forces have arrested at least 14 people.
Hundreds of pro-government demonstrators also rallied in the capital, Tripoli, blocking traffic in some areas, witnesses said.
Protesters answered calls posted online by opposition groups to stage mass demonstrations similar to those that have sprung up around the region in recent weeks. Libya's government, meanwhile, countered by organising rallies yesterday in support of the Libyan leader, Moammar Qadafi, 68, who has ruled the country for more than four decades.
International human rights groups and Libyan dissidents mostly living abroad have accused police of arresting and killing anti-government protesters in recent days.
The extent of violence in Libya is unclear, and accounts difficult to verify. State-owned media have largely avoided reporting on demonstrations save those in favour of Colonel Qadafi.
Peaceful nationwide demonstrations were planned for yesterday to mark the anniversary of a protest in 2006 in which security forces killed at least 12 protesters, according to Human Rights Watch. But protesters got a head start on Tuesday evening in Benghazi, Libya's main commercial centre after Tripoli.
Police in Benghazi arrested at least 14 pro-reform activists and journalists in recent days and on Tuesday they used batons and tear-gas to disperse protesters, according to a report yesterday by Human Rights Watch.
On Wednesday evening, Colonel Qadafi lambasted the United States and its "Zionist" allies in televised speech before a cheering audience, as protests reportedly spread to other towns and cities.
At least 13 people were killed on Wednesday in the city of Al Baida when police opened fire on demonstrators, according to opposition websites quoted by Agence France-Presse.
In Benghazi yesterday, young men clashed with police and burnt down a government office, while security forces in plainclothes but wearing helmets rampaged through the old medina, throwing stones and smashing windows, said a local businessman who asked not to be named for safety reasons.
In Tripoli, police blocked off the city centre from traffic as hundreds of students were bused in for a pro-government rally, according to Agence France-Presse.
As evening fell in Benghazi, growing numbers of protesters led by lawyers rallied outside the city's courthouse to call for democratic reform as police stood by without intervening, the Benghazi businessman said.
"The barrier of fear has been broken, and they're increasing their demands," said the businessman, who was speaking by mobile phone from the scene. "They're saying that they are Libyans, that they are free, that they challenge Qadafi and that we need a constitution."
According to the businessman, the lawyers say they were visited yesterday by representatives of Colonel Qadafi's reform-minded son, Saif al Islam Qadafi, who asked about their demands. The businessman's account could not be verified independently.
"The lawyers told Saif's representatives that they just want freedom," the businessman said.
Colonel Qadafi took power in 1969 in a coup that ousted Libya's pro-western king. Abolishing political parties, he reorganised Libya as a system of committees with himself as "Brother Leader and Guide of the Revolution".
Colonel Qadafi has described that system, known as the Jamahiriya, or "state of the masses", as a form of direct democracy. The country has never had a written constitution and the Libyan leader's critics accuse him of ruling Libya as an authoritarian state bound to his agenda.
For decades, that agenda included support for numerous militant groups and liberation movements, earning Colonel Qadafi the ire of western countries, and ultimately United States and United Nations sanctions on Libya.
All sanctions were lifted after Libya surrendered suspects in the 1988 Lockerbie bombing and in 2003 renounced plans to acquire a nuclear weapon. Since then, the government has gingerly mended ties with western countries, while liberalising its economy to attract foreign investment.
However, the country is still plagued by corruption and high youth unemployment - socio-economic woes that have helped set the stage for anti-government protests in other Arab countries.
Meanwhile, a generation of Libyans increasingly connected to the outside world is starting to demand more accountability from leaders and more liberty for themselves.