Victor Wanyama has rejected a new contract offer from Celtic.
The midfielder is attracting interest from Manchester United, Manchester City and Liverpool.
Wanyama's agent Rob Moore told STV: "Victor has informed Celtic the contract offer fell short of his expectations.
"There were a number of aspects that fell short - he turned it down.
"But it doesn't take a rocket scientist to work out that he lost great earning potential in the summer (by not moving to England)."