More doubts have been raised over Harry Kewell's controversial $A12.26 million move to Liverpool after his official agent broke his silence on the deal.

As the Socceroo made a low-key debut for Liverpool in a pre-season match against German club Cologne, Nikola Mandic confirmed that his brother Bernie had handled all talks with Kewell's old club Leeds United before last week's deal was signed.

Bernie, Kewell's commercial manager, is not registered as an agent with soccer's world governing body FIFA but Nikola is, leading England's Football Association to refer the transfer to FIFA for scrutiny.

Under FIFA rules, only licensed agents are allowed to negotiate on a player's behalf.

But the Mandics say the only people using a non-licensed agent were management at Leeds.

"I am Harry's agent and it is I who negotiated the Liverpool contract," Nikola Mandic told British newspaper the Daily Express.

"With regards to my brother, I don't want to comment on that other than to say what happened between Leeds and Bernie is nothing to do with me.

"I did not get involved because Leeds did not offer Harry a new contract."

Bernie Mandic said: "It is Leeds who are in breach. They have utilised the services of an unlicensed agent."

Bernie Mandic's company MAX Sport collected $A4.9 million on the deal.

Brought to you by AAP © 2024 AAP