British nationals have been caught up in a terrorist incident at a gas field in Algeria where several workers, including an Irishman, have been taken hostage.
Two people are reported to have been killed in the incident but it is understood the 36-year-old married man, from Northern Ireland, is unharmed.
Foreign Office officials in London have confirmed that more than one British national is "caught up" in the terrorist attack on the BP site and Prime Minister David Cameron is to chair a meeting of the Government's crisis committee Cobra on the incident.
A Foreign Office spokeswoman said: "We can confirm that British nationals are caught up in a terrorist incident ongoing near the town of In Amenas at an oil installation near the Algerian border with Libya. The British embassy in Algiers is liaising with local authorities."
Ireland's deputy prime minister Eamon Gilmore has called for the Irishman's immediate release.
"The Government stands ready to use all the resources available to us to ensure that our citizen is released as soon as possible," he said. "I would ask that the family be allowed privacy at this difficult time."
Dublin's Department of Foreign Affairs said it was providing consular assistance to the family and was in close contact with its international partners and a wide range of other contacts in order to establish the facts of the situation.
The emergency British Cobra meeting will be attended by ministers from the Foreign Office and Ministry of Defence as well as officials from other agencies.
No family hotline has been set up for the incident because the number of British nationals involved is "very small", according to officials.
The Foreign Office said it is working with BP to support the families of those involved.