The pair, who both missed last year's World Cup, had been hoping to make their Scotland returns in the Calcutta Cup clash at Edinburgh's Murrayfield ground on February 6.

Dunbar, a centre, has not played for Scotland since tearing knee ligaments in the build-up to last year's clash with the English.

But having recovered from that injury, he suffered a thigh strain in his club's 22-5 win over French side Racing 92 on Saturday. 

Hospital scans confirmed he would be out for at least a couple of weeks.

Back-row forward Ashe suffered a shoulder injury in Glasgow's Champions Cup loss to Northampton a fortnight ago and is also unlikely to be ready to feature until later in the Championship.

"The pair will continue their recovery and ongoing assessment under the care of the Glasgow Warriors medical team," said a Scottish Rugby spokesman.