Algeria, a top oil exporter and one of Europe's biggest natural gas suppliers, has placed multiple officials at its state-run energy company Sonatrach under investigation, including the chief executive, over Sonatrach's natural gas dealings, a senior Algerian oil official said Thursday.

Details into the exact nature of the investigation, which has led to the removal of Sonatrach chief executive Mohamed Meziane, haven't been released.

The probe marks a widening of problems for Algeria's energy sector. The government's imposition of tough contract terms with foreign companies in recent years has pinched investor appetite, raising questions among some analysts whether the North African state will meet upcoming natural gas export targets.

"There is more than one [Sonatrach] official under investigation and the court is now dealing with it," the official said.

Abdelhafid Feghouli, a Sonatrach refining and marketing vice president, has taken over as interim chief executive.

-By Spencer Swartz, +44 207 842 9357; spencer.swartz@dowjones.com