Soldiers sought to put down unrest in Libya's second city on Friday and opposition forces claimed to be fighting troops for control of a nearby town after days of crackdowns Human Rights Watch said killed 24 people.
Protests inspired by the revolts that brought down long-serving rulers of neighbouring Egypt and Tunisia have led to violence unprecedented in the 41-year rule of strongman leader Muammar Gaddafi.
The New York-based rights group Human Rights Watch said that according to its sources inside Libya, security forces had killed at least 24 people over the past two days. Exile groups have given higher tolls which could not be confirmed.
Opponents of Gaddafi had designated Thursday as a day of rage to try to emulate uprisings sweeping through North Africa and the Middle East. Unrest continued well into the night.
The demonstrations have been focussed in the country's east, including its second largest city, Benghazi, where support for Gaddafi has been historically weaker than in the rest of the country. The area is largely cut-off from international media.
"Last night was very hard, there were a lot of people in the street, thousands of people. I saw soldiers in the street," a resident who lives on Benghazi's main thoroughfare, Nasser Street, told Reuters.
"I heard shooting. I saw one person fall down (from a gunshot wound) but I don't have a figure for casualties."
The privately-owned Quryna newspaper, based in Benghazi, said security forces overnight fired live bullets at protesters, killing 14 of them. It published photographs of several people lying on hospital stretchers with bloodstained bandages.
Two Swiss-based exile groups said anti-government forces, joined by defecting police, were battling with security forces for control of the town of Al Bayda, 200 km (125 miles) northeast of Benghazi and scene of deadly clashes this week.
The Libyan Human Rights Solidarity group and the Libyan Committee for Truth and Justice initially said protesters had seized Al Bayda but later said government troops were fighting back. The reports could not be verified.
A source in Benghazi, who said he had been in contact with people in Al Bayda, told Reuters there had been more deaths in that town overnight, adding to at least five killed earlier. "There are a lot of people killed," he said.
Ashour Ahamis, a London-based Libyan journalist, said protesters had stormed Benghazi's Kuwafiyah prison on Friday and freed dozens of political prisoners. Quryna said 1,000 prisoners had escaped and 150 had been recaptured.
CALM IN TRIPOLI
The capital Tripoli has been calmer, with Gadaffi supporters staging demonstrations of their own. The leader appeared in the early hours of Friday briefly at Green Square in the centre of Tripoli, surrounded by crowds of supporters. He did not speak.
A sermon at Friday prayers in Tripoli, broadcast on state television, urged people to ignore reports in foreign media "which doesn't want our country to be peaceful, which ... is the aim of Zionism and imperialism, to divide our country."
Gaddafi's opponents, using social media networks Facebook and Twitter, had called for new protests after Friday prayers, when most Libyan men visit the mosque.
A Benghazi resident told Reuters by telephone the city appeared to be calm after prayers but said local people were unsure what would happen following funerals of people killed in the protests.
Two people in Benghazi, which is about 1,000 km (600 miles) east of Tripoli, told Reuters that Saadi Gaddafi, a son of the Libyan leader and ex-professional soccer player in Italy, had taken over command of the city.
Libya, holder of the Arab League's rotating presidency, said it was postponing a summit planned for Iraq in March, citing "circumstances in the Arab world." But the league's secretariat said it had received no formal notification.
Libya-watchers say the situation is different from Egypt, because Gaddafi has oil cash to smooth over social problems.
Gaddafi is respected in much of the country, though support for him is weaker in the Cyrenaica region around Benghazi.
"For sure there is no national uprising," said Noman Benotman, a former opposition Libyan Islamist who is based in Britain but is currently in Tripoli. "I don't think Libya is comparable to Egypt or Tunisia. Gaddafi would fight to the very last moment," he said by telephone from the Libyan capital.
Muammar Gaddafi's opponents say they want political freedoms, respect for human rights and an end to corruption. Gaddafi describes his political system as true democracy.