Soldiers deployed in the streets of Libya's second city Benghazi on Friday after thousands of people demonstrated over the killing of more than 20 protesters by security forces.
The New York-based rights group Human Rights Watch said that according to its sources inside Libya, security forces killed at least 24 people in crackdowns on Wednesday and Thursday.
The killings occurred after opponents of Muammar Gaddafi, Libya's leader for more than 40 years, designated Thursday as a day of protest to try to emulate uprisings in neighbouring Egypt and Tunisia which ousted entrenched leaders over the past month.
In the early hours of Friday, Gaddafi appeared briefly at Green Square in the centre of Tripoli where he was surrounded by crowds of supporters, but he did not speak.
His opponents called for new protests. "We call on all Libyans to come out after the prayer this afternoon," said an appeal posted on a Facebook page used by opposition activists.
A resident who lives on Benghazi's main thoroughfare, Nasser Street, told Reuters on Friday morning the city was now quiet, with no more demonstrations.
"Last night was very hard, there were a lot of people in the street, thousands of people. I saw soldiers in the street. 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 in the city fired live bullets at protesters, killing seven of them. It cited a security source.
The newspaper published photographs of several people lying on hospital stretchers with bloodstained bandages.
Another resident in Benghazi, who said he had been in contact with people in nearby al Bayda, told Reuters there had been more deaths in that town overnight, adding to at least five killed on Wednesday and Thursday.
"The confrontation between protesters and Gaddafi supporters is still going on, some of the police have become angry. There are a lot of people killed," the resident said.
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.
FIGHT TO THE LAST
Libya watchers say an Egypt-style uprising is unlikely because the government can use oil cash to smooth over social problems and Gaddafi is widely respected, 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.
Two people in Benghazi, which is about 1,000 km (600 miles) east of Tripoli, told Reuters that Saadi Gaddafi, a businessman son of the Libyan leader, had taken over command of the city.
He holds senior military rank and was briefly employed as a player by Italian professional football clubs.
Funerals of those killed were expected in Benghazi and al Bayda on Friday, a potential catalyst for more protests.
Tight controls on media and communications in Libya made it difficult to assess the extent of the violence. But on Friday unverified reports on social network sites said up to 50 people had died. There was no official comment on the violence.
Gaddafi's opponents say they want political freedoms, respect for human rights and an end to corruption. Gaddafi says Libyans enjoy true democracy.
State television showed several hundred pro-government supporters holding a rally in Tripoli's Green Square before dawn. As Gaddafi arrived, he stood up through the sunroof of his limousine and waved to the crowd.
He then got out of the vehicle while the crowd chanted: "He is our leader!" and "We follow your path." Gaddafi left after a few minutes.