Nicolas Sarkozy and his wife Carla Bruni on Thursday launched a legal bid to prevent any further publication of tapes secretly recorded during his 2007-12 term as French president, reports AFP.
In a move that will inevitably fuel speculation the tapes could contain a seriously compromising "smoking gun", lawyers for Sarkozy said they would be filing a request with a Paris court for an emergency injunction against further distribution or publication.
The tapes are thought to contain hundreds of hours of Sarkozy's private conversations with Bruni and close aides. They were recorded by a political advisor, Patrick Buisson, without the couple's knowledge.
Some extracts - without any really explosive content - have already been published, by satirical weekly Le Canard Enchaîné and news website Atlantico.
The revelation of what Buisson was doing whilst working as a close confidante of the centre-right president has sent shockwaves through the French political class.
Lawmakers across the political spectrum have denounced what they have described as an unprecedented act of treachery and, in some cases, a potential threat to national security.
In a statement to AFP, Sarkozy's lawyers said the former president and his supermodel wife had no option but to take legal action.
"The protection of private and secret conversations constitutes one of the foundations of a democratic society and they cannot accept comments made in private being recorded and published without their consent," the lawyers said.
The taped conversations which have been made public so far contain some slightly embarrassing material.
Bruni is heard joking about Sarkozy being a kept man and teasing him that her status as first lady has prevented her from signing lucrative deals to promote wrinkle-creams, unlike actresses Julianne Moore, Julia Roberts and Sharon Stone.
Sarkozy is also revealed to have been rude about some of his ministers.
But that will hardly have come as a surprise to French voters given his reputation for volcanic eruptions. Overall, nothing has emerged so far that is likely to derail his plan to return to frontline politics in time for the 2017 presidential election.
The decision to launch legal action will however inevitably fuel speculation that the tapes contain something more serious that could prove fatal for his comeback ambitions.
Buisson, 64, is a former historian and journalist and a self-styled royalist with links to the far right.
He was blamed by many in Sarkozy's UMP party for pushing his boss too far to the right, particularly on issues of crime, race and immigration, making the president appear as a divisive rather than a unifying figure.
That shift in the latter years of Sarkozy's term is credited by many analysts as being a key factor in his defeat by the Socialist Party's Francois Hollande in the 2012 presidential election.
Buisson is currently being investigated by an examining magistrate over suspicions that his company was illegally awarded lucrative contracts for carrying out opinion polls by Sarkozy's office.
Read more of this report from AFP.