Suspected Islamist militants have kidnapped at least six oil industry staff in southern Algeria and killed two. Initial reports said those seized included Britons, French, Norwegians and Japanese.
The British-based giant BP said there was a "security incident" at the Amenas gas field in Algeria. Beyond that it had no more confirmed details, it said.
Two people were killed, including a foreigner, and several others injured, according to Algerian media.
The Algerian news agency APS said Islamist militants had attacked a base for oil workers at Tinguentourine, some 40 kilometers (25 miles) from Ain Amenas, where BP operates a gas field in partnership with the Algerian concern Sonatrach and the Norwegian energy group Statoil.
Mauritania's ANI news agency, which has direct contacts with Islamists, said an al Qaeda-linked group operating in the Sahara had claimed responsibility for the kidnapping.
A diplomat quoted by the French news agency AFP said the Algerian army had launched an operation to try to free the captive staff.
An unnamed Algerian security official quoted by Associated Press (AP) said the militants came from Mali. The incident had begun before dawn Wednesday and the army had since surrounded the militants and their hostages.
On Monday, the Algerian foreign ministry had said Algeria was closing its border with Mali, where France has begun an intervention against al Qaeda-linked Islamist rebels.
Governments seek clarification
Algeria's El Watan newspaper said the hostages included two French nationals and one Japanese national working for Japan Gas Corporation.
The British, Japanese and French foreign ministries said they were trying to obtain more information.
A British Foreign Office spokeswoman described the incident as "ongoing."
"We are urgently seeking clarification from oil companies in the area as to whether they have personnel involved in the incident," the spokeswoman said.
Norway's Statoil said more than 10 of the around 20 workers at a gas production facility were Norwegians, but did not say if any had been harmed.
ipj/rc (Reuters, dpa, AFP, AP)