One of France's most respected newspapers, Le Monde, says it is filing a lawsuit accusing the office of President Nicolas Sarkozy of spying on its journalists.
The paper says the presidency used the intelligence service to identify one of its sources.
Le Monde says the government was angry about its coverage of a funding scandal involving Mr Sarkozy's party.
The president's office rejected all of the paper's claims.
It said it had "never given a single instruction" to investigate Le Monde's sources.
The newspaper says the president's office was annoyed by a story it ran in July naming Labour Minister Eric Woerth in connection with an investigation into the finances of France's richest woman, L'Oreal heiress Liliane Bettencourt.
The authorities are investigating whether she made illegal donations to Mr Sarkozy's election campaign in 2007.
The president and Mr Woerth, who was the treasurer of Mr Sarkozy's party at the time, have denied any wrongdoing.
BBC News
