The Guardian is to defend robustly a legal action seeking to force the disclosure of the documents that formed the basis of its Paradise Papers investigation.
The offshore company at the heart of the story, Appleby, has launched breach of confidence proceedings against the Guardian and the BBC.
In legal correspondence, Appleby has also demanded that the Guardian and the BBC disclose any of the 6m Appleby documents that informed their reporting for a project that provoked worldwide anger and debate over the tax dodges used by individuals and multinational companies.
Appleby is also seeking damages for the disclosure of what it says are confidential legal documents.
The documents were leaked to the German newspaper Süddeutsche Zeitung, which shared them with a US-based organisation, the Pulitzer-prize-winning International Consortium of Investigative Journalists (ICIJ).
The ICIJ coordinated the Paradise Papers project, which included 380 journalists from 96 media organisations across 67 countries. The consortium included the New