Ayumi has sold nearly 50 million albums

The 29-year old wrote on her blog that her left ear "doesn't work anymore" and that it was inoperable.

The star is thought to have tinnitus, a ringing in the ear that can be caused by constant exposure to sound.

Ayumi is Japan's top-selling singer scoring 28 number one hits and has sold nearly 50 million albums.

She has known of her condition since going in for an ear check last year, according to her website.

'Continue singing'

"Nevertheless, I would like to continue as a singer. That's why I would like to continue singing until I reach the limit with my remaining right ear," she wrote on her members-only fansite.

"I won't stop. I won't make excuses. As a professional, I would like to deliver the best performance for everyone."

Ayumi is due to launch her second tour of Asia in April to mark her 10th anniversary as a performer.