A British national caught up in a terrorist attack in Algeria has been killed, according to local reports.
The Foreign Office said UK workers are involved in the incident at a BP oilfield near the border with Libya but officials could not confirm reports of the killing.
A 36-year-old Irishman is among the group of workers taken hostage in the early hours by a group claiming to be al Qaida but is believed to be unharmed.
APS, the country's state news agency, said the Briton was the second person to die.
A French national is reported to have been killed during the raid, which comes after militant Islamists vowed to retaliate for France's military intervention, supported by British military equipment, against rebels in Mali.
Prime Minister David Cameron is chairing a meeting of the Government's crisis committee Cobra on the terror attack, which is being attended by ministers from the Foreign Office and the Ministry of Defence.
Ireland's Tanaiste (deputy prime minister) Eamon Gilmore has called for the immediate release of the Irish hostage.
He said: "The Government stands ready to use all the resources available to us to ensure that our citizen is released as soon as possible. I would ask that the family be allowed privacy at this difficult time."
Heavily-armed gunmen in vehicles are reported to have stormed the energy site in In Amenas, in the east of the African country, taking a group of up to 20 international workers hostage.
It is understood at least some of the captive workers were being kept in their own living quarters at the compound and were being allowed access to telephone and email. The natural gas complex is a joint venture of BP, Norway's Statoil and the Algerian Sonatrach company.