Appleby, a leading offshore law firm at the center of the so-called Paradise Papers hack, has turned to Osborne Clarke for legal advice as it plans a potential legal action against the British Broadcasting Corp. and Guardian Media Group plc, owner of The Guardian newspaper.

Osborne Clarke, a leading U.K. firm, will represent Appleby as the latter confirmed its plans to launch breach of confidence proceedings against both news outlets. Ashley Hurst, a commercial litigation partner at Osborne Clarke in London, has taken the lead on the matter for Appleby.

Appleby’s plans were leaked to Suddeutsche Zeitung, the German newspaper that broke the news nearly two months ago about that hack at the offshore firm and which then shared its data with the International Consortium of Investigative Journalists (ICIJ).

The Guardian reports that Appleby has demanded that it and the BBC disclose any of the six million documents obtained from the firm to inform their reporting following the massive hack, which now has its own dedicated page on the ICIJ’s website. The Guardian has confirmed that it intends to defend against any legal action initiated by Appleby.

“Our overwhelming responsibility is to our clients and our own colleagues who have had their private and confidential information taken in what was a criminal act,” said Appleby in a statement. “We need to know firstly which of their—and our—documents were taken. We would want to explain in detail to our clients and our colleagues the extent to which their confidentiality has been attacked. Despite repeated requests, the journalists have failed to provide to us copies of the stolen documents they claim to have seen. For this reason, Appleby is obliged to take legal action in order to ascertain what information has been stolen.”

While The Guardian declined to comment, the BBC issued a statement defending its decision to publish stories based documents leaked from Appleby.

“The BBC will strongly defend its role and conduct in the Paradise Papers project,” the publicly financed U.K. broadcasting company said. “Our serious and responsible journalism is resulting in revelations which are clearly of the highest public interest and has revealed matters which would otherwise have remained secret. Already we are seeing authorities taking action as a consequence.”

Appleby is one of the world’s best known offshore firms. The Bermuda-based firm also has offices in the British Virgin Islands, Cayman Islands, Hong Kong, Mauritius, Seychelles and Shanghai, as well as the tax-friendly U.K. Crown dependencies of Guernsey, the Isle of Man and Jersey. Appleby’s major clients include companies such as Apple Inc., Glencore plc, Nike Inc. and Uber Technologies Inc., as well as Big Four accounting firms like Ernst & Young, KPMG and PricewaterhouseCoopers, according to the ICIJ.

At the time of the hack, the firm said in a statement that having “thoroughly and vigorously investigated the allegations,” it was satisfied that they were “satisfied that there is no evidence of any wrongdoing, either on the part of ourselves or our clients.”

The ICIJ has said that the Appleby documents reveal “how deeply the offshore financial system is entangled with the overlapping worlds of political players, private wealth and corporate giants, […] that avoid taxes through increasingly imaginative bookkeeping maneuvers.”

Allen & Overy, Berwin Leighton Paisner, Clifford Chance and Clyde & Co were among a number of Global 100 firms to have their names emerge in the Appleby documents.