Robert Snodgrass has left Leeds' training camp after being given permission to speak to an unnamed Barclays Premier League club, believed to be Norwich.
Canaries manager Chris Hughton revealed last night that the npower Championship club had rejected an approach for the Scot last week.
But Whites manager Neil Warnock said this morning that Snodgrass had now been allowed to leave the training base in Cornwall to discuss terms with another club, who he did not name.
He told leedsunited.com: "Negotiations have been going on for weeks.
"I was hoping he would have had a change of heart and I can honestly say that in all my time in football, I've never worked as hard in trying to keep a player.
"He was offered the best contract, the captaincy, and we would have built a team around him so I am very disappointed.
"He's made it clear what he wants to do and he's had his head turned. He wants to play in the Premier League. He believes his Scotland international career may be better served in the Premier League, but I'm not so sure."
Warnock added: "The club is in the process of due diligence and there's not a lot concrete we can say to him.
"He's seen and heard a lot of things over the past few years. But I am still disappointed. Very disappointed. Life moves on though."
Following a friendly win at Celtic last night, City boss Hughton told Press Association Sport: "We did put a bid in for (Snodgrass) a week or so ago and that is where we are at.
"He is a player we would like, hence the reason we made the bid, but of course he is a Leeds United player and until we are told otherwise that will be the case.
"I would like to strengthen the squad but it has to be the right player because we have a good squad with good morale and good mentality, as showed last season.
"It is important that the right player will enhance what we've got and give us the right competition in the right areas."
Snodgrass replaced Andy Lonergan as club captain following Warnock's appointment in February, and won both Leeds fans' player of the year and players' player of the year awards for the 2011/12 season.
Warnock added on the club's official website: "He's always said he wants to play in the Premier League, although I'm not sure it's a great move because I think another year would have suited him.
"But he's in the last year of his contract and players are in charge of the situation at that stage.
"The fans know that I'm doing everything I can and we have to make sure we cover the loss of Rob. We do need a couple of quality signings and we're talking to a number of prospects at the moment.
"Unfortunately you can't keep a player if he wants to go. You can do your best, but your hands are tied sometimes, and we've tried every way we can to get him to stay, but in the end it wasn't possible."
The Scotland international joined Leeds from Livingston in 2008, making 168 league appearances and scoring 41 goals in all competitions.