Lens have accused Chelsea of showing a lack of respect over their raid for Gael Kakuta.
Chelsea have been banned by FIFA from signing players until January 2011 over their capture of Gael Kakuta from Lens.
The Lens president, Gerard Martel, told The Independent yesterday: "It is a logical punishment for a club that goes to intermediaries who turn the heads of young players on behalf of them. Someone who worked for Chelsea must have told them there was a way of getting him out of here. I have got my idea who it is, but I am not going to say.
"I have worked for football for 21 years and there has always been respect from clubs when we sit around a table [to discuss transfers]. But when Chelsea steal a player that is not acceptable. I was the president of the UCPF [body representing French professional football clubs] for 15 years. I know what we are doing is exactly right."
