Argentina defender Heinze has asked for a three-man panel to decide whether United gave the player permission to leave the club for an agreed fee, according to a Premier League spokeman.

The three-man panel will be made up of a judge or lawyer, a Premier League representative and a third person experienced in football administration.

Liverpool made a 6.8 million pounds offer for Heinze several weeks ago, but United refused to sell him to their arch rivals despite the player claiming he has a letter from United allowing him to leave for that price.

Heinze is keen to leave Old Trafford and has hired Liverpool's lawyers to help him.

The 29-year-old arrived back in England last weekend after being given time to recover from the Copa America and met United manager Sir Alex Ferguson on Monday to discuss his future.

He insists he will be totally professional while he remains with the champions.

"I've fulfilled my duties by returning for training and I will now carry on like a professional," Heinze told the Daily Mail on Tuesday.

"I will keep on coming to training and see what happens. I have a muscle injury in my leg but it is only minor and will not keep me out for long.

"I've spoken with the coach (Ferguson) and I have insisted that my wish is to leave the club if a big offer appears on the table.

"Today the only such offer is from Liverpool and it is this that is causing the problem. Earlier in the summer I received a promise from United that I could leave if the deal was good for both parties and at the moment there is an offer from Liverpool."