Freshfields Bruckhaus Deringer’s Frankfurt office has been raided by German prosecutors in connection with a tax evasion investigation.

Reuters reported that the raid was connected to an investigation into so-called “cum-ex” transactions, which are at the center of one of the largest tax scandals in Germany.

The asset-stripping deals have allegedly been used by a number of banks in Germany to claim billions of euros in rebates from authorities in the country before a loophole was closed in 2012. The loophole effectively allowed two parties to claim ownership of the same shares, enabling both parties to receive the rebates.

German newspaper Sueddeutsche Zeitung, which broke the news of the raid on Freshfields, claimed that it related to an opinion that the Magic Circle firm had prepared for Canada’s Maple Financial Group Inc. The German arm of the bank, which was raided by German authorities in connection with the tax evasion investigation in 2015, was closed by German authorities last year amid worries that unpaid taxes were threatening its financial position.

“Freshfields is confident that the prosecutor’s review will reveal that our advice has been legally sound,” the London-based legal giant said in a statement.

Earlier this year, Jones Day’s Frankfurt office was raided by German authorities investigating its client, auto giant Volkswagen AG. Jones Day had carried out an internal investigation into an emissions-rigging scandal at Volkswagen.

A German court later ruled that documents seized in the raid could not be used by investigators looking into the scandal. Freshfields also had a role representing Volkswagen, having advised on the company’s $4.3 billion settlement with the U.S. Department of Justice.