Scotand's Six Nations prospects have suffered another blow with confirmation that Richie Gray has been ruled out of the remainder of the tournament by the arm injury he sustained in the loss to Wales at BT Murrayfield on Sunday.

The 25-year-old lock, the only Scot to figure in a Test match on the Lions' tour to Australia two years ago, is expected to be out of action for three or four months, a devastating blow for his club, Castres, who are battling the spectre of relegation in the French Top 14 Championship at the moment.

Gray picked up his injury midway through the second half of the 23-26 loss to Wales. While ther problem seemed minor at first, a scan subsequently revealed that the former Glasgow Warriors and Sale player had suffered tendon damage. A decision on whether surgery will be required will be made at a later date.

Gray has been replaced in the squad by Tim Swinson, the Glasgow second row who also celebrated his 28 th birthday yesterday. Swinson has played nine times for Scotland and scored a try for the Warriors against Zebre last weekend, helping them to the 54-10 win that moved them to the top of the Guinness PRO12 table. Swinson's most recent outings for Scotland were on last summer's tour, when he played against Argentina and South Afroca.

It also seems likely that Glasgow prop Gordon Reid will play no further part in the Six Nations. The unfortunate Reid, who had come on as a replacement for Al Dickinson, lasted just three minutes before he was taken off with a serious head knock, but it has now emerged that he also suffered a serious knee injury, damaging his medial collateral ligament.

Although no prognosis has been suggested, Reid's injury could be season-ending and could even put his involvement in the Rugby World Cup later this year in doubt. His problem is likely to mean a return to frontline action for his Glasgow clubmate Ryan Grant, who was left out of the original Scotland squad last month as he was on trial for assault, but was subsequently reinstated after the case against him was found not proven.

Scotland's injury problems have become desperate in recent weeks, with Adam Ashe, Sean Maitland, Duncan Weir, Grant Gilchrist, Ruarish Jackson, Chris Fusaro, Dave Denton, Jon Welsh and Tommy Seymour all currently sidelined. Coash Vern Cotter also has an anxious wait to find out if Finn Russell, who was yellow-carded for a challenge on Wales fly-half Dan Biggar, will face any further punishment after being cited for the same offence.