Security sources told Algerian state news agency APS that nearly 100 overseas workers had been released - and put the total originally seized by Islamist militants at 132.
At least ten UK citizens are understood to remain at risk as local efforts continue to end the terrorist attack at a remote desert gas facility.
The Algerian Government said last night that a significant number of foreigners had been freed in an operation led by its own special forces but an unspecified number had been killed.
It remains unclear how many of those still in the complex are alive.
Prime Minister David Cameron said Britain would do everything we can to hunt down those behind the brutal and savage episode which is well into its third day.
But he publicly expressed his frustration that he had not been pre-warned of the special forces assault, in which some foreign workers were killed.
It was reported that two UK workers were among the casualties, which would bring the British death toll to three after one was killed in Wednesday's initial raid by Islamist militants.
The foreign hostages are from eight different countries and many Algerians are held captive.
Footage of several British workers said to have escaped the siege has been shown on Algerian state television.
"I feel safe at the moment but I wont feel 100 per cent happy until I'm back in the UK," said Darren Matthews, Senior E&I Atex Engineer at In Amenas.
"My heart goes out to the guys that are still there and hopefully everyone comes home safe because, at the end of the day, it's only work."
Another man said he was very relieved to be out. He added: "As much as I'm glad to be out, my thoughts are with colleagues that are still there at the moment."
The Foreign Office has sent a plane carrying consular crisis staff to within 280 miles of the facility amid continued efforts by joint operator BP and the Government to evacuate UK workers.
There are also reports from a Mauritanian news site that the militants are demanding the release of two terror figures in US jail, including 1993 World Trade Centre bombing mastermind Omar Abdel Rahman, in return for the release of two US captives.
Mr Cameron met US defence secretary Leon Panetta, who was already in London on other business, in Downing Street for talks about the crisis.
After the meeting he took the chair for the days second meeting of the Government's emergency committee, Cobra.
APS said the unconfirmed figures also put at 573 the number of Algerians freed by special forces and efforts to force out the militants were going on.
It quoted a security source as saying they were "still trying to find a peaceful end".
Mr Cameron, who cancelled a trip to the Netherlands to make his long-awaited speech on the EU so he could remain in the UK to oversee the crisis, gave an update to MPs in the Commons.
The number of British citizens believed killed, injured or missing had been quite significantly reduced since reports that they numbered around 30, he said.
Other reports put the number at ten and it is believed that is much closer to the true picture but fuller details are being held back for fear of aiding the terrorists.
Mr Cameron was told of the military raid only after it was under way when he telephoned Algerian prime minister Abdelmalek Sellal yesterday morning, to the dismay of No 10.
He told MPs that he would not hide the fact that he was disappointed not to be informed in advance and the UK had offered to help in any way we can.
"They were facing the situation where there was imminent threat to life and we should bear that in mind," he added, describing the contacts as good.