Portsmouth have been fined £15,000 and players' agent Willie McKay given a suspended ban after being found guilty of breaching Football Association rules during the transfer of Benjani Mwaruwari to and from the club.
The club and agent were found guilty at an independent regulatory commission hearing on Monday.
Agents are not allowed to act for two different clubs in two consecutive transactions involving the same player. It was found that McKay acted on behalf of Auxerre when Benjani moved to Portsmouth in January 2006. He then acted for Portsmouth when the Zimbabwe striker moved to Manchester City in January this year.
McKay was given a suspended ban - if there are any further breaches of the FA's agents regulations in the next two years, he will be suspended from taking part in any transactions involving English clubs for the duration of one transfer window.
Portsmouth will face a further £15,000 fine if they breach any rules during the next two years.
Commission chairman Paul Gilroy QC stated after the hearing: "The Football Agents Regulations were introduced as an important method of addressing unacceptable practices in professional football, particularly in the transfer market.
"Both parties were fully aware of the new regulations at the time the offences were committed. The commission considered that the justice of the case was met by imposing penalties which to a large degree will act as an incentive to both parties to avoid any future transgressions."
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