The Nairobi Coffee Exchange (NCE) said on Tuesday that out of the 20,729 bags offered, some 12,898 were sold, an improvement from last week when buyers only took up 8,148 of the 20,714 bags offered.

"There is a big concern over the quality of crop being offered to the market as the present season draws to a close," Charles Mbaluka, the chief executive of the NCE told Reuters.

During this week's auction, Grade AA sold at $174-$302 per bag compared with $191-$312 last week, the NCE said in a market report.

Grade AB fetched $147-$226 per bag compared with the previous week's $146-$200 per bag.

Overall, the beans fetched a total of $2.6 million with the average price coming at $170.19. Last week, the beans fetched a total $1.6 million with the average price coming in at $160.16.

"Overall the performance was much better compared to last week despite persistent concerns over quality," Mbaluka said.

"We hope both prices and volumes will stabilise when the new season sets in and quality beans enter the market," he said.

Although Kenya is a small coffee producer compared to producers such as Brazil and Vietnam, its speciality beans are much sought after for blending with those from other countries.