Representatives of national news organisations will today meet financial service regulators who have requested the hand over of leaked documents relating to a possible takeover bid by the Belgian brewer Interbrew.
The brewer, which produces Stella Artois, claims the documents were leaked in order to rig the market and the Financial Services Authority has started a criminal investigation.
The company started legal proceedings last December against The Independent, The Guardian, The Times, The Financial Times and Reuters news agency, and won a ruling in the Court of Appeal that the leaked documents should be handed over.
Last week, Interbrew accepted that The Independent should not be forced to hand over its documents because they were acquired in a different manner from those sent to other news organisations.
The brewer has issued contempt of court proceedings against The Guardian, which will be heard next Tuesday and could result in sequestration of assets or a large fine.
Interbrew said that it had singled out The Guardian because the newspaper insists that the documents are not in its possession but are held by the journalist who received them, and it is not willing to compel him to give them up.
The media organisations believe the case raises crucial issues over confidentiality and the protection of journalistic sources. They are taking the case to the European Court of Human Rights in Strasbourg.
MPs, led by Tom Watson, a Labour member of the home affairs select committee, last night tabled a Commons motion saying that "a free press is vital to a democratic life" and that journalists were under moral and professional obligations to protect sources.