The families of two BP employees killed in the 2013 In Amenas gas plant attack in Algeria have filed a lawsuit in London's High Court against the company, accusing it of failing to take reasonable steps to protect its workers. Islamist militants' attack on the plant in January 2013 killed 40 people, most of them foreign nationals.

"Our clients have now commenced court proceedings to help them secure the justice they seek following the deaths of Carlos and Sebastian," said Clive Garner, leading the case at law firm Irwin Mitchell on behalf of the families of BP employees Carlos Estrada Valencia, 44, and Sebastian John, 26, who were both killed during the attack.

In February last year an inquest criticised BP and its joint venture partners over security at the plant, where armed guards meant to protect the facility were stationed 1 kilometre away from the site and the entrance gates to the accommodation compound were found to have been left open.

BP said several of its entities are facing similar civil claims in the Texas state court that were brought by individuals injured in the incident and some families of workers killed.

The London court case was filed last week and a trial could be more than a year away, a spokesman for Irwin Mitchell said.

BP, one of three partners with Norway's Statoil and Algeria's Sonatrach in the In Amenas joint venture plant, said it understood proceedings against certain BP entities had been issued in the London court.

"BP remains deeply saddened by the tragic events at In Amenas ... It is the terrorists who are responsible for the deaths and injuries that occurred because of the attack," a spokesman said.