Singer Bjork has pulled out of two festival performances in Europe next month due to ongoing voice issues.

The star was forced to scrap the final two dates of her Buenos Aires residency in Argentina and her headlining set at the Sonar Sao Paulo festival in Brazil last month after doctors found a nodule on her vocal cords.

The Icelandic artist had aimed to rest and be back on stage in time for a performance at the Primavera festivals in Barcelona, Spain and Porto, Portugal, beginning on June 2, but her recovery hasn't gone as planned.

A statement released by festival bosses on Wednesday reads: "After canceling (sic) some shows due to an inflamed nodule, Bjork's specialist doctor advised her to keep resting and not to continue with the shows as they could bring a permanent damage to her voice. We are very sorry about any inconvenience this might bring, and appreciate your understanding. We wish Bjork a quick and full recovery to continue enjoying her talent soon."

Fans have been offered refunds for the cancellation.