Nigerian army troops have destroyed at least 27 illicit refining sites and seized stolen crude oil following raids this week on illegal oil bunkering sites in the Niger River delta, an army spokesperson said on Wednesday.

Large-scale oil theft and sabotage of pipelines have hobbled output from Nigeria, Africa's top energy producer, and crimped exports in recent years, crippling government finances and leaving President Bola Tinubu with one of his biggest challenges.

Acting army spokesperson Danjuma Jonah Danjuma said around 100,000 litres of stolen crude were seized during the raids. Three vehicles loaded with illegally refined fuel were also seized.

The raids are part of ongoing operations to curb oil theft, Danjuma said in a statement.