Ghana's 45,000 barrel-per-day state-run Tema oil refinery shut its main crude distillation unit on August 28 after running out of feedstock, two sources with knowledge of the plant's operations told Reuters on Monday.

Ghana is Africa's newest crude oil exporter after starting up its offshore Jubilee field, but the country's sole refinery in Tema requires upgrades to be able to run the domestically produced oil and generally relies on imports from Nigeria.

We don't have crude to process so the main plant is not working at the moment, one of the sources said, adding the refinery was waiting for a cargo from Nigeria. He did not say when the cargo was expected.

We have not had a smooth production in the past months - today there is crude, tomorrow there is no crude - it's been an off-and-on situation since the beginning of the year and its getting worse, the source added.

The Tema refinery has been hobbled by repeated shortages in available crude since 2008, when its main lender Ghana Commercial Bank cut off support due to unpaid debts. Ghana's government repaid the debt earlier this year.

The repeated outages at the Tema plant have led to shortages of domestic supplies of fuel, particularly of cooking fuel, and could weigh on the government of President John Atta Mills ahead of next year's elections.