Newport Gwent Dragons defence coach Rob Appleyard has admitted Welsh regions are finding it hard to compete with the French clubs' financial clout.
Dragons wing Aled Brew is the latest Welsh player to move to France after opting to join Biarritz.
With a salary cap set to be introduced next season, Appleyard says Welsh clubs will find it hard to keep hold of top players.
"We are unfortunately going to lose some of our players," he said.
"We can't really compete with the funding they've got out there [in France].
"I think at the moment, as you can see throughout Welsh rugby, there is a little bit of a target towards our senior players in all of the regions."
The Welsh region had hoped that the 25-year-old would sign a new deal, and his decision to leave was described as "disappointing" by Dragons chairman Martin Hazell.
It is a view shared by Appleyard, a member of head coach Darren Edwards' backroom team at the Dragons.
"Obviously losing any of our senior players and a top performer like Aled is disappointing," added Appleyard.
"As a group and as a squad we're disappointed to lose a player of his potency and his attacking force and he's a great guy in the environment as well.
"As a group of coaches, we're desperate to try and keep a number of players and contracts have been offered to those players."
Wales forwards Dan Lydiate and Toby Faletau are under contract, and Appleyard believes they will play an important role in the region's development over the coming seasons.
"Both of those players have committed to us for the next couple of years," added the former Wales flanker.
"It's definitely two players who we can build our team around.
"As we saw last weekend [for Wales], both of them are in outstanding form at the moment.
"[When] they've played for us they've shown that outstanding form."