Britain is playing a co-ordinating role in military operations to help foreign nationals leave Libya, the prime minister's spokesman has said.
Some 50 Britons and 150 foreign nationals have arrived in Malta on HMS Cumberland as part of this operation.
Earlier, David Cameron chaired a meeting of the National Security Council focusing on developments in Libya and the wider region.
He has urged Libyan leader Col Muammar Gaddafi to "go now".
The prime minister said the country had no future "that includes him".
Some of those who left Malta on HMS Cumberland, in the latest stage of the British evacuation operation, have spoken of their experiences of the unrest in Libya.
Marsden Sims, 63, a civil engineer from Tonyrefail near Pontypridd, told the MoD locals had burnt a reading room at his site and looters had targeted cars and property.
"We didn't have direct trouble to begin with but when word spread from the TV reports things got quite agitated," he said.
"We were in one works compound at Messla and a few nights ago we saw looters outside taking vehicles and equipment."
And 25-year-old Natalie Brooks, who is returning home to Birmingham with her son Mustafa and daughter Naimah, told the MoD: "We thought it safer with the security situation to get out and bide our time.
'Serious pressure'
"Where we lived in the city was not particularly affected by the fighting, but you don't know if the situation is going to get more dangerous."
The UK has frozen Col Gaddafi's British-held assets and those of his family, and withdrawn their diplomatic immunity.
Business Secretary Vince Cable has imposed an export ban on Libyan banknotes, which are printed in Britain. The authorities in Tripoli had asked permission to export an estimated £900m worth of currency to Libya, prompting fears the money could be used to fund further repression of anti-government protesters.
Mr Cameron said the measures, which followed a UN Security Council agreement to impose sanctions, were designed to show "just how isolated" Col Gaddafi regime was.
The prime minister added: "We are now putting serious pressure on this regime."
Meanwhile, Foreign Secretary William Hague has called for an immediate end to violence against anti-government demonstrators in Libya and warned Col Gaddafi's supporters that there will be a "day of reckoning" for anyone involved in human rights abuses.
Addressing a meeting of the United Nations Human Rights Council in Geneva, Mr Hague said there must be "no impunity" for those involved in violence against protesters.
He said: "We have signalled that crimes will not be condoned, will not go unpunished and will not be forgotten.
"This is a warning to anyone contemplating the abuse of human rights in Libya or any other country: Stay your hand. There will be a day of reckoning and the reach of international justice can be long.
"We must now maintain the momentum we have attained to ensure that there can be no impunity for crimes committed in Libya and to help bring about an immediate end to the violence."
BBC political correspondent Carole Walker said the "vast majority" of Britons who were in Libya and wanted to leave are now out.
Aircraft shooting
"There is a small number who still want to leave and British officials are in touch with them and are looking at ways of getting them out of the country," she added.
Our correspondent said there may be other Britons in Libya who have "decided for whatever reason that they are going to stay in the country".
Earlier, the prime minister paid tribute to the bravery of the British special forces who carried out a mission on Sunday to rescue stranded desert oil workers from a number of countries.
Three RAF Hercules aircraft were involved in the operation to rescue 150 people. One of the planes was shot at above an air strip to the southwest of Benghazi.
Some of those rescued described the moment the Hercules was shot at, forcing it to abandon a landing.
One British oil worker said: "The aircraft took two hits on the right hand side of the fuselage, you just heard 'bang bang' as the rounds actually struck."
'Ready to assist'
Another said after failing to land at two blocked off fields, the Hercules was trying again at a third when the firing started, forcing them to abort.
The Ministry of Defence confirmed that one of its C130 aircraft appeared to have suffered "minor damage consistent with small arms fire", adding that "there were no injuries to passengers or crew and the aircraft returned safely to Malta".
On Saturday, another 150 oil workers, many of them British nationals, were rescued from the desert by two RAF Hercules and flown to the safety of Malta.
They later caught flights back to the UK, which arrived at Gatwick airport on Sunday and early on Monday.
The government said HMS York remained in the region and was "ready to assist as required".
It has closed the British embassy in Tripoli, leaving a skeleton staff working in a different building.
source : bbc.co.uk
