Bernie Mandic has defied FIFA to uncover any wrongdoing in Harry Kewell's 2003 transfer to Liverpool.

FIFA's probe, which began in mid-May, continues as the Kewell camp weighs up whether to pursue a re-trial of his defamation case against former England captain Gary Lineker after the initial trial resulted in a hung jury and no verdict this week.

FIFA is seeking documents related to Kewell's connections to the Mandic camp, with Bernie Mandic acting as his unregistered manager and brother Nick Mandic as his FIFA-licensed agent.

"I challenge anyone at FIFA to find a single discrepancy of any kind," Bernie said.

FIFA began the investigation, co-incidentally just as the trial was about to get underway, after concluding the matter came within its constituency.

Initially the transfer of Kewell from Leeds United to Liverpool was approved by the English Football Association with no role for FIFA.

"Because it was an internal transfer between Lees and Liverpool, it was quite complex legally to decide under whose jurisdiction it was," a FIFA official was quoted to say in London's Evening Standard.

"It is now resolved that it is FIFA's and the matter is being investigated."

The transfer caused great controversy at the time, with STG5 million ($A11.84 million) paid by Liverpool, of which STG3 million ($A7.1 million) went to cash-strapped Leeds and STG2 million to Mandic's companies.

Bernie Mandic said the majority of that STG2 million was money owed to him by Leeds for work done toward buying a majority stake in then-NSL club Sydney Olympic - work that was abandoned when Leeds fell into a financial black hole.

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