The cost of bringing a claim against a bank in the London courts has skyrocketed with claimants exposed to costs of up to £10m, say senior litigators.

The debate over costs follows a string of high-profile civil litigation and investor claims against banks such as Barclays and Lloyds Bank filed at the High Court in recent months.

Sources close to the disputes have accused the banks of deliberately ramping up costs to price litigants out of the market.

One source close to the RBS £4bn shareholder case said: “We are seeing precious little evidence that the banks are making economies in their costs.”

Another litigator added: “Disclosure is the key area where costs can balloon. In the current Libor litigation brought by Property Alliance Group against RBS the bank raised the spectre of disclosure exceeding 30 million documents.

“It is unlikely any organisation in the UK has the bandwidth to process that. It’s becoming enormously expensive.”

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