The In Salah gas plant in Krechba was hit by explosive munitions from a distance, it said.
The plant is also part-owned by BP and Algerian state company Sonatrach.
The Algerian army is securing the area, officials said. The facility has been closed down, BP said.
No group has yet claimed responsibility for the attack.
Fighters from Al-Qaeda in the Islamic Maghreb, the so-called Islamic State and other jihadist groups are active in remote parts of Algeria.
Security around energy infrastructure was tightened after Islamist militants seized another gas plant owned by Statoil and BP in 2013.
The army stormed the In Amenas facility after a four-day stand-off. At least 37 hostages were killed.
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