Uganda's coffee exports plummeted 28.5% year on year in August, hurt by a drought that blighted crops in parts of the country and squeezed yields, the coffee industry regulator said.

The east African country shipped a total of 501,054 60-kg bags of coffee in August, compared with 700,990 bags exported in the same month last year, Uganda Coffee Development Authority (UCDA) said in a report seen by Reuters on Wednesday.

"The decrease in exports was mainly attributed to lower yields this year that were characterized by drought in most regions," UCDA said.

The drought led to a shorter main harvest season in central and eastern parts of the country which hit yields, the regulator said.

Uganda, which predominantly cultivates robusta, is Africa's largest exporter of coffee followed by Ethiopia. Earnings from the beans are one of the country's largest sources of foreign exchange. (Reporting by Elias Biryabarema; Editing by George Obulutsa and Alexander Winning)