LONDON, July 18 (Reuters) - JP Morgan must stop

suing directors of fintech Viva Wallet in Greece, London's High

Court ruled on Friday, in the latest round of a bitter legal

battle over the Greek startup.

The U.S. bank brought a lawsuit in Athens in January against

Viva's CEO Haris Karonis and three other directors, seeking 916

million euros ($1.1 billion) as part of a dispute over JP

Morgan's investment in Viva.

Viva's majority shareholder Werealize and the Viva directors

responded by applying for an anti-suit injunction in London to

stop JP Morgan pursuing its case in Greece.

Judge David Foxton granted Karonis and the other directors

an anti-suit injunction, on the grounds that suing in Greece was

a breach of JP Morgan and Werealize's shareholders' agreement.

Both Werealize and JP Morgan claimed victory after Friday's

ruling, as the two sides also did last year when the High Court

ruled on their respective call options to purchase the other's

Viva shares.

Werealize's spokesperson called on JP Morgan to "engage in

productive discussions" about Viva's future, adding: "JPM must

now step aside and allow Viva to continue growing and reach its

full commercial potential."

JP Morgan, however, pointed to the court's rejection of many

of Werealize's arguments, including that the Greek lawsuit was

hopeless or oppressive.

"While we will continue to address their litigious tactics,

and many matters are still being resolved by the courts, our

commitment remains steadfast to the business and our

investment," a spokesperson for the bank said.

JP Morgan bought a 48.5% stake in Viva Wallet, which is used

by businesses in southern Europe, for nearly 810 million euros

in 2022, while Karonis' Werealize owns 51.49%.

In January, the Court of Appeal ruled that JP Morgan

effectively had "one shot" at exercising its call option to

acquire Werealize's shares, though the parties' dispute over

whether that has taken place has not yet been resolved.

JP Morgan and Werealize and its directors have also filed

defamation lawsuits against each other in Greece. Foxton said

the business relationship has been "acrimonious, albeit a

fruitful one for the legal community" in Britain and Greece.