Ulster back-row forward Stephen Ferris has undergone surgery to repair an ankle tendon injury.

The Ireland international picked up the injury during his side's Pro12 clash with Edinburgh at the start of November, ruling him out of Ireland's autumn series.

There is now a major question mark over his availability for the remainder of Ulster's Heineken Cup pool fixtures.

A statement from Ulster read: "Stephen will be reviewed in the coming weeks to establish an accurate time period for recovery and to assess when he will fit to return to play."