The Financial Conduct Authority (FCA) infringed the rights of Achilles Macris by failing to give him the right of reply to its report into the affair, a London tribunal ruled on Thursday.

Macris ran the London division of JPMorgan's Chief Investment Office, where Bruno Iksil, nicknamed "the London Whale" for the size of his derivatives trades, stacked up losses of more than $6.2 billion (3.7 billion pounds).

Macris, a Greek citizen, appealed against the findings of the watchdog's report in October.

In its report on the 137.6-million-pound ($231 million) fine it levied on the bank over the losses, the FCA did not mention Macris by name but said that "by virtue of the conduct of the CIO London management", JPMorgan had deliberately misled the regulator.

Macris argued that the FCA had infringed his rights and unfairly prejudiced him in the notice without giving prior notice or a right of reply.

In a statement published on its website on Friday, that FCA said the tribunal ruled that Macris "was identified in the notice and therefore should have been afforded third-party rights".

The FCA said it was seeking permission to appeal against the decision.

If the FCA fails to win an appeal, Macris could bring a separate case to determine whether the FCA's criticisms were justified.

In an emailed statement sent on Macris' behalf, law firm Clifford Chance said "he looks forward to challenging the findings made against him ... which fail to take proper account of the actions he took and mischaracterise his dealings with the

FCA".

JPMorgan agreed to pay $920 million in penalties last year to the U.S. Federal Reserve, the U.S. Securities and Exchange Commission, the U.S. Comptroller of the Currency and the FCA over the trading scandal.

Iksil's former boss, Javier Martin-Artajo, and junior trader Julien Grout were indicted in the U.S. in September on five charges each, including securities fraud and conspiracy, for seeking to hide losses as they began to mount. Iksil has not been criminally charged and has been cooperating with U.S. authorities.

Martin-Artajo and Grout are not in the United States and have not returned to face the charges. Macris was Martin-Artajo's supervisor.

($1 = 0.5961 British Pounds)

(Reporting by Clare Hutchison; editing by Erica Billingham and Tom Pfeiffer)

By Clare Hutchison