Lens company secretary Didier Roudet has hit out at Chelsea over the Gael Kakuta affair.
Fifa have banned Chelsea from registering any new players in the next two transfer windows after the French club made an official complaint over the signing of Kakuta in 2007.
Fifa's Dispute Resolution Chamber (DRC) found in Lens' favour and ruled that the Blues were 'jointly and severally liable', while Kakuta, a regular in Chelsea's reserve side, was also banned from playing for four months and fined £680,000.
Chelsea are also liable over Kakuta's fine, and will have to pay Lens £113,000 in compensation, although they are appealing.
Roudet described Kakuta as a 'jewel' in L'Equipe, believing he could have earned the club millions of euros in a future transfer if he had been allowed to develop further at Lens.
"He could have played here, made people happy and got points for the club," he said.
"And in a latter transfer we could have earned 15 or 20 million euros. We have been deprived of all that.
"The club can't stand the robbery of such a fantastic boy on any level, and moreover a real lover of the area."
Meanwhile, Chelsea's French scout Guy Hillion, the man who discovered Kakuta, explained what happened after his first talks with the player's mother.
He said: "Mrs Kakuta told me she talked with her son and he was attracted by Chelsea.
"As she didn't know a lot about juridical elements of the case, she was expecting advice.
"I set up the whole file and introduced him to Chelsea. Then, both parties have found an agreement."
He has previously said that Kakuta's mother told them that no contract had been signed with Lens, but the widower later unveiled paperwork which is understood to be a pre-contract, although she has since claimed ignorance of what this agreement meant.