Islamist militants attacked a gas production field in southern Algeria on Wednesday, kidnapping at least nine foreigners and killing two people including a French national during a dawn raid, local and company officials said.
The raid, claimed by an al Qaeda affiliate, came after Islamists had vowed to retaliate for France's military intervention in Mali, where its forces have been in action against al Qaeda-linked militants since last week.
The attack also raised fears that the French action could prompt further Islamist revenge attacks on Western targets in Africa, where al Qaeda in the Islamic Maghreb operates across borders in the Sahara desert, and in Europe.
The al Qaeda group said it had carried out Wednesday's raid on the In Amenas facility in Algeria, Mauritania's ANI news agency reported.
The Algerian interior ministry said: "A terrorist group, heavily armed and using three vehicles, launched an attack this Wednesday at 5 am against a Sonatrach base in Tigantourine, near In Amenas, about 100 km (60 miles) from the Algerian and Libyan border."
The gas field is operated by a joint venture including BP , Norwegian oil firm Statoil and Algerian state company Sonatrach.
A French national was killed in the attack, a local source said, but it was unclear if the victim was one of those kidnapped.
Algeria's official APS news agency said that one security guard had been killed and seven people were injured including two foreigners.
Five Japanese nationals working for the Japanese engineering firm JCG Corp were kidnapped as well as a French national, local officials said. An Irishman was also seized, the Irish government said, while a diplomatic source said an American had been kidnapped.
Also kidnapped was a Norwegian gas worker, the newspaper Bergens Tidende said, quoting the man's wife.
"I received a phone call from my husband this morning and he said he was kidnapped," the woman said. The Norwegian Foreign Ministry could not confirm the report.
The Algerian interior ministry said the attack was directed at bus taking gas field workers to an airport. The number of hostages remained unclear.
The foreigners were taken from In Amenas in the morning. Algerian troops had mounted an operation to rescue the hostages and had also surrounded the workers' camp at Tiguentourine, a local source said. A French source said that the raiders had come from Libya.
Algeria has allowed France to use its air space during its military intervention against al Qaeda-linked Islamist rebels in Mali, although officials have yet to make a link between Wednesday's attack and the conflict in Algeria's southern neighbour.
ANI, which has regular direct contact with Islamists, said that fighters under the command of Mokhtar Belmokhtar were holding the foreigners seized from the gas field.
Belmokhtar for years commanded al Qaeda fighters in the Sahara before setting up his own armed Islamist group late last year after an apparent fallout with other militant leaders.
BP confirmed there had been a "security incident" at the In Amenas field but could give no more details.
Statoil, a minority shareholder in the venture, said it was notified of the incident on Wednesday morning but could not say if any of its fewer than 20 employees were affected.
Statoil described the incident as serious and called it an emergency situation.
BP said the field was around 1,300 km (825 miles) from the capital, Algiers.
The five Japanese work for the engineering firm JGC Corporation, Jiji news agency reported, quoting company officials. JGC has a deal with Sonatrach-BP-Statoil Association for work in gas production at In Amenas.
A reporter for Japan's NHK television managed to call a JGC worker in Algeria.
The worker said he got a phone call from a colleague at the gas field. "It was around 6 a.m. this morning. He said that he had been hearing gunshots for about 20 minutes. I wasn't able to get through to him since."
The Japanese Foreign Ministry in Tokyo said it was gathering information on the situation but could not comment. French Foreign Ministry officials also said they had no immediate comment and were trying to verify the reports.
France troops launched their first ground operation against Islamist rebels in Mali on Wednesday in a crucial action to dislodge al Qaeda-linked fighters who have resisted six days of air strikes.