Bluegrass star Alison Krauss is recovering from an undisclosed illness which prompted her to cancel a prestigious date at New York’s Carnegie Hall last week.

The singer, who is about to embark on a major tour with new musical partner Robert Plant, was billed to appear with jazz great Bobby McFerrin and bassist Edgar Meyer, but was too ill to take to the stage.

The concert, which took place without her, was part of McFerrin’s Perspectives series of themed shows at Carnegie Hall.

Krauss’ tour with Plant is scheduled to begin in Louisville, Kentucky in April (08).