Scotland are refusing to admit defeat in their efforts to include Steven Shingler in their RBS 6 Nations squad, despite the International Rugby Board advising that the player is only eligible to play for Wales.
The Scottish and Welsh rugby unions had asked the IRB to review Shingler's eligibility after Wales challenged his selection in Andy Robinson's 36-man Scotland panel due to his appearance for Wales Under-20s against their French counterparts last year.
Scotland believed the 20-year-old London Irish centre or fly-half was available for selection through his Dumfries-born mother, and insisted he had kept his eligibility open by refusing to sign a declaration tying him to Wales.
But the world governing body said that IRB Regulation Eight, which governs eligibility, indicated that Shingler can only play for Wales, as the Under-20's fixture he had played in was sanctioned as being between the nominated second XV's of the competing nations, thus committing him to the principality.
An IRB statement said: "The IRB has reiterated to both Unions that during 2011 both Wales and France officially designated their Under 20 team to be the next senior national team.
"As the IRB has been advised that Shingler represented Wales Under 20 against France Under 20 in 2011 it would therefore indicate that he is tied to Wales and ineligible to play for any other Union."
But the SRU and WRU have the option of utilising IRB Regulation 2, which would allow them to refer the matter to be considered formally by the governing body's Regulations Committee.
And the SRU have wasted little time in confirming that they plan to refer the matter to the committee, as well as re-iterating that they are fully supportive of Shingler.
A SRU statement read: "We remain fully supportive of the player and his sincere desire to represent Scotland and we intend to refer this matter to the IRB's Regulations Committee in order that it can consider the case formally in accordance with IRB Regulation 2."
During the saga the SRU had also cited the cases of former Wales Under-20 internationals James Loxton and Matthew Jarvis, who moved to Connacht last year and are eligible to play for Ireland despite having played against a France Under-20's side in 2010.
But it is understood the WRU argued that the status of the 2010 fixture was different from the 2011 game that Shingler was involved in, and the union expressed their approval at the outcome.
Their statement said: "The WRU welcomes the IRB announcement which confirms that proper procedures were followed when informing the 2011 Wales U20 team to play France they would be solely Wales qualified at senior level after taking part in the game.
"It is important that all players informed of their potential senior selection status now or in future are left in no doubt about the authority of the regulations and protocols in place.
"The case of Steven Shingler being named as an RBS 6 Nations Scotland squad player could not be left untested because of the impact on all other players."