ALGIERS - Islamist militants attacked a gas field in Algeria on Wednesday, claiming to have kidnapped up to 41 foreigners including seven Americans in a dawn raid in retaliation for France's intervention in Mali, according to regional media reports.The raiders were also reported to have killed three people, including a Briton and a French national.The attack in southern Algeria also raised fears that the French action in Mali could prompt further Islamist revenge attacks on Western targets in Africa, where al-Qaida in the Islamic Maghreb (AQIM) operates across borders in the Sahara desert, and in Europe.AQIM said it had carried out Wednesday's raid on the In Amenas gas facility in OPEC member Algeria, Mauritania's ANI news agency reported.Armed men BP said armed men were still occupying facilities at the gas field, which produces 9 billion cubic meters of gas a year (160,000 barrels of oil equivalent per day), more than a tenth of the country's overall gas output, and 60,000 barrels a day of condensate.APS said a Briton and an Algerian security guard had been killed and seven people were injured. A French national was also killed in the attack, a local source said. Also among those reported kidnapped by various sources were five Japanese nationals working for the Japanese engineering firm JGC Corp, a French national, an Irishman, and a number of Britons.The US State Department said it believed some US citizens were also among the hostages, while Norway said 13 of its nationals were involved.A member of an Islamist group styling itself the "Blood Battalion" was quoted by Mauritanian media as saying that five of the hostages were being held at the gas facility and 36 were in a housing area. APS said the Islamist raiders had freed Algerians working at the gas facility."The operation was in response to the blatant interference by Algeria and the opening of its air space to French aircraft to bomb northern Mali," the Islamist spokesman told Mauritania's ANI news agency.Security implications The attack was the first time in years that Islamist militants are known to have launched an attack on an Algerian energy facility.The attack could have implications for security across the whole of Algeria's energy sector, which supplies about a quarter of Europe's natural gas imports and exports millions of barrels of crude oil each year.Such an attack would require a large and heavily armed insurgent force with a degree of freedom to move around, all elements that al-Qaida has not previously had.However, the conflict in neighboring Libya in 2011 changed the balance of force. Security experts say al-Qaida was able to obtain arms, including heavy weapons, from the looted arsenals of former leader Muammar Gaddafi.French troops launched their first ground operation against Islamist rebels in Mali on Wednesday in an action to dislodge from a strategic town al-Qaida-linked fighters who have resisted six days of air strikes.