The Scottish Rugby Union is defending the selection of Steven Shingler in the Scotland Six Nations squad after their Welsh counterparts questioned his eligibility.
The 20-year-old Swansea-born, London Irish first five-eighth or centre was named on Thursday as one of six uncapped players in Scotland head coach Andy Robinson's 36-man squad as preparations for the February 4 Calcutta Cup clash with England at Murrayfield began in earnest.
However, the final say in whether Shingler will be permitted to play for Scotland is now set to come from the International Rugby Board after a row over his eligibility.
Shingler played at fullback for Wales under-20s against France under-20s in the 2011 Six Nations, when both nations declared the age-group squads as their second XVs, effectively handcuffing the players involved to those nations.
The Welsh Rugby Union said in a statement: "All the U20 players who represented Wales against France at U20 level in 2011 were informed that they would then become Wales-qualified players only at senior level."
However, Scotland, who believe Shingler qualifies as a result of his Dumfries-born mother, have been assured by the player he kept his eligibility open by refusing to confirm his future would lie with Wales.
The SRU responded in a statement, which read: "Steven has confirmed to Scottish Rugby that he declined to sign a declaration from the WRU that he was committed solely to representing Wales at senior level.
"Steven has informed us that he made it clear that he wished to leave open his international eligibility as he was also eligible to represent Scotland and England as well as Wales.
"Scottish Rugby believes we have acted in good faith in this matter and have also taken cognisance of an IRB ruling last year concerning two players who played for Wales under-20 against France under-20 in 2010 who now play for Connacht and are eligible for Ireland.
"We are liaising with the IRB on this matter."
The SRU were referring to a ruling relating to Matthew Jarvis and James Loxton in which a precedent may have been set allowing Shingler to feature for Scotland.
Robinson hopes Shingler will be the first of many possible recruits as he follows the lead of Scotland football coach Craig Levein in scouring all possible avenues for potential international players.
Scotland attack coach Gregor Townsend contacted Shingler after the player had been monitored for a year.
Talks gathered pace towards the end of 2011 and Shingler declared his allegiance to Scotland.
Shingler is listed by London Irish as a No.10, but has also played second five-eighth this season.
World Cup semi-finalists Wales are well covered in both positions and their stance could be for fear of losing talent other than Shingler in a similar situation.
Shingler, whose brother, Aaron, has represented Wales at sevens and is therefore ineligible for Scotland, outlined his credentials after being confirmed in the squad.
Prior to the WRU's statement, Shingler told www.scotlandrugbyteam.org: "I would be massively proud to play for Scotland.
"My upbringing from my mother means I've always known about Scotland."
Part of the remit of Scott Johnson, who is to join Scotland at the end of the domestic season as senior assistant coach, will be to scout for players with Scottish pedigree, while Edinburgh's prolific Holland-born wing Tim Visser will qualify through residence in June and is poised to travel on the summer tour to Australia, Fiji and Samoa.
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