The striker is seeking a move back to Spain in the transfer window.
He has not played for Chelsea since the FA Cup final in May, following which he claims manager Antonio Conte sent him a text, telling him he was not in his plans for the new season.
Costa was interviewed at home in Brazil on the same day Chelsea lost their opening Premier League game to Burnley and said he was refusing the club’s demand to return to play with the reserves.
“They want me to be there training with the reserves. I wouldn’t be allowed access to the first-team dressing room and I would have no contact at all with the guys,” he told the Daily Mail.
“I’m not a criminal! I don’t think it is fair after all I have done to be treated like that.”
The Brazilian-born Spain international, who joined Chelsea from Atletico Madrid in 2014, said if the club did not allow him to move before the transfer window he was prepared to see out his contract unpaid in Brazil.
“I am open to being a year in Brazil without playing, even if Chelsea fine me for a year and don’t pay me.
“I’ll come back stronger. If I was in the wrong, I’d go back now and do as they say.
“I want the deal with Atletico resolved this month. My idea would be to go to Madrid, train there, get in the best physical shape and be ready to fire ahead of the World Cup.”
The situation is complicated by the fact that Atletico are currently banned from signing players in this window although a loan deal would be possible.
Costa’s relationship with Conte appears to have broken down although the Brazilian accepts the Italian “is a good coach”.
Last week Conte said there was “no news” on the Costa situation but earlier this summer said the “situation is closed.”