The Ivory Coast international submitted a transfer request on Tuesday, and has now travelled to France for a medical after Leeds accepted a bid for the 23-year-old.
"It is with a heavy heart that I have asked to leave Leeds United," the fan favourite told the club's official website.
"It was a difficult decision for me as Leeds has been a wonderful place to live and to play football.
"However, I have made the decision based on my career development, and the opportunity to play at the highest level in France is too big an opportunity to turn down.
"I want to thank all the Leeds United fans who loyally follow the team up and down the country as you have made my time at the club very special. I also want to thank Simon Grayson, my team-mates, and everyone at the club for all your help and support, and giving me the opportunity to play for this great club.
"I am sure that it will not be long before Leeds United return to the Premier League and I wish you every success in the future."