The data, confirmed by the world's fifth largest cocoa grower's Cocoa and Coffee Interprofessional Board (CCIB), showed that exports fell by 7.7 percent compared with the 27,636 tonnes for the same month the previous season.

Month on month, exports doubled from the 12,308 tonnes reported in August.

NCCB and CCIB officials as well as traders blamed the drop on heavy rainfall and overcast skies, which slowed down the drying process and damaged unpaved roads.

"I am sure you are aware the heavy rains we witnessed since mid-August this year not only hampered proper drying of beans but also led to an outbreak of the black pod disease," said Theophile Mbarga, a buyer and trader from the Centre Region.

Cameroon's cocoa season runs from August 1 to July 31, with the main crop harvest running to January/February, followed by the smaller mid-crop harvest.

The number of exporters rose to 24 in September, up from 18 in August.

Olam Cam, a subsidiary of Singapore commodities firm Olam topped the monthly export chart with 5,671 tonnes, up from 4,163 tonnes the previous month.

Exports by Cargill's joint venture partner Telcar Cocoa Ltd rose to 4,050 tonnes 1,204 tonnes, while Cameroon Marketing Commodities (CAMACO) exported 4,100 tonnes, up from 2,909 tonnes in August.

The Central African country exported 180,000 tonnes of cocoa during the 2011/12 season, down from the 200,083 tonnes the previous year, due to a prolonged dry season and attacks by pests and diseases.