After meeting with Real president Ramon Calderon, Wagner Ribeiro said: "I told Calderon we have a proposal of 32million euros (£25.4m) from Chelsea and that Robinho wants to leave.
"But Calderon said he would not sell for 100m euros (£79.25m).
"I left the meeting thinking that was that, but after talking to other leaders of the club I saw that this position might change."
Ribeiro was travelling to London for talks with Chelsea yesterday and, in the interview with Brazilian website Globoesporte, he added: 'Robinho said to Calderon that he was treating him the same as (FIFA president) Sepp Blatter said that Manchester was doing with Cristiano Ronaldo.
"That is, slavery.
"Madrid don't want to release the attacker, in the same way Manchester was with the Portuguese.
"If they don't let Robinho go, he will continue, sad, and in the coming year will be worth far lower than the value currently offered by Chelsea."
Robinho has two years left on his Real Madrid contract.