Barton is still waiting to complete his move to St James' Park

Magpies boss Sam Allardyce is furious that the �5.5m switch has stalled over a �300,000 fee possibly owed to Barton.

"I've spoken to City's chief executive Alistair Mackintosh, Joey and his agent and I intend talking to Sam," said PFA official Mick McGuire.

"We're looking for an amicable conclusion," he added.

Barton, 24, is contractually entitled to the pay-off if he leaves the club without requesting a transfer, but City are refusing to give him the money because they say he was not forced to leave.

Allardyce is angry with City for the hold-up and said: "They're out of order. I'm flabbergasted and want the situation resolved.

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"I cannot understand it because City didn't pay anything for this player as he came through the youth system and they are selling him for over �5m.

"All I know is that this is a matter for Joey to sort out and I hope it is resolved as it has stopped him putting pen to paper."

West Ham also agreed a fee with City for the England midfielder but after meeting Newcastle officials last month, Barton decided to move to St James' Park.