Striker Jordan Rhodes has asked Blackburn to give him permission to speak with Middlesbrough over a move.
The 25-year-old Scotland international has reportedly been the subject of a £12m bid from the Teesside club.
Rhodes joined Rovers for a club-record £8m from Huddersfield in 2012.
"I have been advised by the club that they have rejected an offer from Middlesbrough for my services which was in excess of what Blackburn paid for me," Rhodes told ESPN FC.
"I am ambitious and have never hidden my desire to play at the highest level possible and that was one of the reasons why I left Huddersfield Town for Blackburn.
"When I left Huddersfield I felt the timing was right in the next stage of my career and, having seen Middlesbrough's performances last season in reaching the play-off final and their ambition this summer in terms of acquisitions, I would have liked to have been able to talk to them and I am unhappy at not being given that opportunity."
He has scored 74 goals in 143 appearances for Rovers.