Rhys Webb

Webb, who missed the Six Nations because of the injury, is set to leave Ospreys for Toulon at the end of the season.

That switch will make him ineligible to play for Wales, the most recent of the scrum-half's 33 caps coming in December against South Africa.

A statement from Ospreys' medical team read: "Rhys pulled out of Wales' Six Nations campaign and went on to have surgery on an ongoing knee problem.

"He will be unavailable for the remainder of this season and his focus is now on getting his recovery right for next season."

The halfback, who has 31 caps, was released from the squad on Thursday and the Welsh Rugby Union confirmed he will undergo further assessments "to establish the best course of action".

Webb's setback leaves head coach Warren Gatland potentially without nine senior players ahead of the opening clash at home to Scotland on February 3.

Webb has been replaced by uncapped Cardiff playmaker Tomos Williams but Gatland will be missing a host of experienced names for most, if not all, of the Six Nations.