Nigeria suffered the biggest decline among members of the Organization of Petroleum Exporting Countries (OPEC) during August. The organization’s monthly oil market report for September showed that Nigeria’s crude oil production declined by 130,000b/d, reaching 1.468mb/d in August from 1.52mb/d in July, Punch reported.

Nigeria struggles to maintain oil production rates as companies face difficulties to repair pipelines in Niger Delta following severe attacks by militant groups, according to Vanguard.

In March, the country lost its status as Africa’s top oil producer to Angola when oil production decreased to 1.677mb/d, compared to Angola’s 1.782mb/d. In July, Nigeria recorded its biggest increase in production at 1.75mb/d of oil. However, this did not help the country regain the top spot from Angola.

In related news, OPEC’s crude oil production stood at 33.24mb/d in August, a decrease of 23,000b/d from July’s volume. Crude oil output increased mainly from Saudi Arabia and Iran, while Nigeria and Libya showed the largest drops.