According to BP's website, In Salah started production in 2004 from three fields Krechba, Teguentour and Reg. In February, it announced the start up of development of the Gour Mahmoud, In Salah, Garet el Befinat and Hassi Moumene fields, to bring output to 9 billion cubic metres a year.
The 2013 In Amenas attack was carried out by militants linked to veteran Algerian jihadist Mokhtar Belmokhtar, who U.S. forces say may have been killed in an air strike in Libya last year. Al Qaeda has denied he was killed.
Belmokhtar's group Al Murabitoun or "Those who sign in Blood" has been blamed for several attacks across the region. Al Qaeda in the Islamic Maghreb has also claimed recent attacks in the Ivory Coast, Mali and Burkina Faso.
Attacks and bombings in Algeria, one of Europe's main gas suppliers, have become rarer since the North African country emerged from a 1990s war with Islamist fighters that killed around 200,000 people.