If Charteris was to move to the Stade Aime Giral, he would team up with compatriot James Hook who switched to the south of France in January, while Mike Phillips swapped Ospreys for Bayonne in the summer and full-back Lee Byrne joined Clermont Auvergne.
Edwards, whose side's Amlin Challenge Cup hopes now hang by a thread after the 23-19 loss to Exeter Chiefs on Sunday, admits he is upset by the departure of Charteris and something has to be done.
He said: "I'm disappointed, but Luke is a very honourable guy.
"I think everyone is trying to steal our Welsh players at the moment. It's a huge worry and we are all feeling the heat in Wales.
"We are working hard to produce players for the national team and we cannot capitalise on these. We need to get our heads together and solve it.
"These players employ agents and it is their job to move them to another club."