Norwegian oil company Statoil says it will resume operations at a gas field in Algeria, 19 months after five Norwegian workers were killed in a terrorist attack there.

Statoil ASA says it has decided to reopen the Ain Amenas plant after "outstanding security operations" were implemented.

The move follows similar action at the oil and gas company's other Algerian plants, which were put back into operation a year ago and in early 2014 after improved security measures.

Statoil said that Algerian authorities had also introduced security measures" beyond those implemented by the joint venture."

In January 2013, terrorists took 37 people hostage at the Ain Amenas natural gas plant, including 12 Statoil employees, which led to a four-day siege by Algerian forces in which 29 al-Qaida-affiliated militants were killed.