David Cameron has postponed a long-awaited speech on the UK's relationship with Europe due to the on-going hostage situation in Algeria.
The British prime minister was expected to set out his vision for the UK's future role in the European Union, including the prospect of a referendum.
He described the situation in Algeria as "very uncertain and very fluid".
The Conservative leader had been under pressure from many of his MPs to give a binding commitment to a vote on Europe.
Algerian forces have moved against Islamic militants holding hostages at a gas facility in eastern Algeria, the state news agency reports.
Reports quoting militants said at least 34 hostages and 14 kidnappers died.
Militants also told Mauritania's ANI news agency that seven foreign hostages were still alive after the Algerian military raid.
Nearly 600 Algerian workers and four foreign hostages - two from Scotland, one from France and one from Kenya - were freed during the operation, APS reported.
Militants had earlier said they were holding 41 foreign nationals. They were believed to include British, Japanese, US and Norwegian citizens.