Lee scored 41 goals in 122 Rotherham outings

Lee, 24, handed in his request after Rotherham's Carling Cup victory over York on Tuesday and the Millers had little choice in letting the forward go.

His contract with them ran out at the end of the season when he could have left for nothing.

But they will now get �850,000 for Lee and the fee could rise to �1.2m based on appearances and goals as well as if Cardiff achieve promotion to the Premiership.

Lee left the door open for a Bluebirds approach last weekend, stating: "I would be excited by a move to Cardiff, I'm at the time in my career when the next move is crucial."

Rotherham signed Lee for �150,000 in September 2000 and manager Ronnie Moore is expected to be given a large part of the transfer fee to sign a replacement.