BAMAKO, Nov 25 (Reuters) - New gold discoveries in Mali have increased the West African country's gold reserves to 881.7 tonnes at the end of October, or around 15 years of output at current production levels, a mines ministry official said on Friday.

Mali is Africa's fourth-largest gold producer after South Africa, Ghana and Sudan, with about 13 mines operated by multinational companies including Barrick Gold, B2Gold and Resolute Mining.

B2Gold Corp currently accounts for the bulk of reserves, with 162.9 tonnes of gold. It is followed by Barrick Gold Corp with 141.9 tonnes and Resolute Mining, which has 131.1 tonnes, the head of the mines ministry's audit and statistics department Mamadou Sidibé told Reuters.

"The increase in reserves is the result of exploration," he said.

Mali's industrial gold production in 2021 totalled 63.4 tonnes. Sidibé in October warned that production risked falling short of annual forecasts this year after underperforming through the third quarter. (Reporting by Tiemoko Diallo Writing by Sofia Christensen Editing by Mark Potter)