South African utility Eskom has asked consumers to conserve energy after revealing that it is running low on coal stocks at some of its power stations.

The company has confirmed that ten of its power plants have less than three weeks’ of coal supplies left and some have less than ten days’ worth of supplies in their reserves, local media reported.

Eskom told local media that its fuel supply problems are the result of a major supplier, owned by the Gupta family, entering bankruptcy protection. The company is attempting to secure new contracts with other companies.

Eskom is also moving coal supplies from other facilities to help reduce the shortages. It said that the supply shortages are particularly challenging as it typically experiences higher levels of demand in the winter season.