London Irish fly-half Steve Shingler has found himself at the centre of a row between the Welsh and Scottish rugby unions.
Shingler was named in Scotland's Six Nations squad despite playing for Wales at U20 level in 2011.
Swansea-born Shingler played for Wales U20s against France U20s last year, meaning that he would only be able to play for Wales in the future.
"Steve Shingler played for Wales U20s against France in 2011 before which he was specifically informed, as were his fellow squad members, that the match would confirm their sole qualification as potential Wales senior international candidates," the WRU said in a statement.
"Shingler was told by the U20 team management that if he played in the game he would become a Wales qualified player and therefore ineligible for selection for any other nation.
"The regulations and guidelines relating to qualification compliance are set in accordance to IRB regulations and any questioning of these regulations should be directed to the IRB.
"We have made the IRB aware of this issue today and will be returning to it as a matter of urgency in the morning."
However, the SRU believe that Shingler qualifies for Scotland as a result of his Dumfries-born mother.
"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," the SRU responded.
"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. We are liaising with the IRB on this matter."
Shingler was one of six uncapped players named in Andy Robinson's 36-man squad.
