Cardiff - Wales full-back Leigh Halfpenny's decision to leave Cardiff Blues at the end of the season led to calls for the future of Welsh rugby to be "sorted now" if more players were not to take up lucrative offers in France.
Although the Blues didn't name Halfpenny's new side, they said he had been the target of a French club with "significant resources that we simply cannot compete with at this current time".
Halfpenny has been widely reported to be joining French big-spenders Toulon, the reigning European champions, with Britain's Daily Telegraph estimating his salary in at 395,000 (479,791 euros, $656,156) a year.
The 25-year-old was the man of the tournament for Wales when they won the Six Nations last year and followed that up by being named man of the series in the British and Irish Lions subsequent 2-1 Test triumph in Australia.
Halfpenny has won 48 caps and scored almost 350 points for his country. He made his Blues debut in 2008.
However, his current Cardiff contract expired at the end of this season and he now seems poised to join a Toulon side already boasting such talents as England great Jonny Wilkinson and South Africa's Bryan Habana.
Should he head to France, Halfpenny will follow in the footsteps of Wales colleagues Jamie Roberts, Dan Lydiate, Mike Phillips and James Hook in playing in the French Top 14, with centre Jonathan Davies (Clermont Auvergne) and lock Ian Evans (Toulon) also due to cross the Channel later this year.
Welsh rugby is currently in the middle of a bitter dispute between the four professional regions and the national Welsh Rugby Union regarding the future of the senior club game, with issues of competition structure and revenue all to be resolved against a backdrop of uncertainty concerning next season's European Cup.
Cardiff chief executive Richard Holland said that, in the circumstances, the "outstanding" Halfpenny's decision was no surprise.
"We put our very best offer on the table, but he has been the target of a major European club with significant resources that we simply cannot compete with at this current time," Holland said.
Holland, who insisted Halfpenny left with the Blues' best wishes, added: "Given the current uncertainty over the competitions the regions are playing in next season and revenues attached to that, it is understandable why players are looking elsewhere.
"The threat to Welsh rugby and our ability to keep top players in Wales is highlighted by the fact the French game is underpinned by broadcast revenues that dwarf anything we receive from our domestic league.
"It's not surprising that Welsh players would choose the certainty of strong weekly French competitions over the uncertainty of the weekly club competition in Wales.
"The future of the game in Wales must be sorted out now -- this situation simply cannot be allowed to continue."
Halfpenny's move was announced just a day after Wales coach Warren Gatland said he was resigned to more of his squad being targeted by overseas clubs.
"Ideally, we would like players playing in Wales, but I am under no illusions, given the success of the Wales team and some players with the Lions," said Gatland, who coached the combined side in Australia.
Wales begin the defence of their Six Nations title against Italy in Cardiff on 1 February.