Reports from Libya indicate thousands may have been killed or injured as the government crackdown escalates "alarmingly", UN human rights head Navi Pillay has said.For the past week, fighting has raged between anti-government forces and troops loyal to Libyan leader Col Muammar Gaddafi, in power for 42 years.
Witnesses in Tripoli say pro-Gaddafi forces have opened fire on protesters.
Nato ambassadors are holding emergency talks.
Around the capital, Tripoli, an elite brigade commanded by Col Gaddafi's son Khamis is believed to be dug in.
'Appalling violence' The UK and France are pushing for an arms embargo and a war crimes investigation.
Britain is to send a second ship, HMS York, to deploy to the sea area near Libya.
"The violence we have seen is appalling and unacceptable," said Prime Minister David Cameron. "People working for this regime... should remember that international justice has a long reach and a long memory."
AnalysisInternational efforts to co-ordinate a response to the Libya crisis are clearly gathering pace, after some criticism that it's taken too long.
A number of European nations have been mobilising their militaries to assist in evacuation efforts. With increasing military assets arriving on the scene, some Nato members clearly think co-ordinating and supporting these efforts is something that perhaps Nato could and should do.
Any alliance involvement is likely at first to be limited to that. But international concern over events has been mounting, and questions are being raised about what contingencies - including military ones - are being planned, should the situation on the ground deteriorate further, and foreign nationals become stranded.
There continues to be talk of a possible no-fly zone. Would Nato become involved in that? The obstacles include whether there is an appetite or a consensus to establish one, whether it would really have much impact, and who might enforce it.
For Nato, Italy and France probably have the nearest suitable air bases, or perhaps Greece. Otherwise, it might be a case of the United States, France, Italy or Spain deploying aircraft carriers. Clearly, that would be a major step.
Evacuations by sea continued on Friday, somewhat hampered by rough weather.In Paris, Libyan opposition supporters occupied the Libyan embassy. Both the ambassadors to France and to the UN cultural agency Unesco have announced they are joining the opposition.
Libyan state TV has said the government will give each family 500 dinars (£250; $400) to cover increased food costs, while some public sector workers will receive a pay rise of 150%.
However, much of the country is now in the hands of anti-government forces.
International response In Geneva, the UN Human Rights Council is meeting in special session for the first time to discuss the crisis in Libya. Libya is an elected member of the council but some members have called for it to lose its seat.
"In brazen and continuing breach of international law, the crackdown in Libya of peaceful demonstrations is escalating alarmingly with reported mass killings, arbitrary arrests, detention and torture of protesters," said Ms Pillay, UN High Commissioner for Human Rights.
The UN World Food Programme has said Libya's food supply chain is at risk of collapse because imports were not getting into the country and food distribution is hampered by violence, the AFP news agency reports.
End Quote Anonymous eyewitness TripoliIn the past two days, some of the public buildings that have been partially burnt and are still standing were whitewashed in what looks to be an attempt to hide scorched parts that are visible to the naked eye from the outside”
Nato ambassadors are meeting in emergency session on Friday afternoon. Nato secretary general Anders Fogh Rasmussen has said Nato has no intention of intervening in Libya.However, thousands of foreign nationals from Nato member states have been fleeing the violence in Libya, which has gripped much of the country in the past week.
The evacuations posed a "massive challenge", Mr Rasmussen said.
Col Gaddafi has blamed the uprising on al-Qaeda, saying young people had been given hallucinogenic drugs to incite them to revolt.
Help for UK nationals
- The Foreign Office is advising against all but essential travel to Libya
- UK nationals in Libya wishing to get on the charter flight are advised to call the following numbers:
- 020 7008 0000 from the UK or 021 3403644/45 from within Libya
There was fierce fighting in western towns on Thursday, as pro-Gaddafi forces tried to regain control of areas seized by the opposition.A resident of Tripoli, who did not want to be identified, said the city was living in fear.
"We have families who are not allowed to take the bodies of the deceased... unless they sign papers declaring they were shot by the opposition to the current regime," the man told the BBC
"There haven't been funerals going on where obviously if you don't have a body you don't have a funeral. People haven't been picking up their deceased."