Former French president Nicolas Sarkozy and his wife Carla Bruni are to file a legal complaint over secret audio recordings made of them by an adviser during the 2012 election campaign, lawyers for the couple said yesterday.

Revelations that Patrick Buisson, part of Sarkozy’s inner circle, recorded hours of talks with the conservative leader and his entourage have caused uproar in the opposition UMP party weeks before local elections.

Sarkozy is expected by many to contest the 2017 presidential election after his defeat by Francois Hollande two years ago.

“Mr Nicolas Sarkozy and Mrs Carla Bruni-Sarkozy cannot accept that remarks made in private were recorded and published without their consent,” lawyers Thierry Herzog and Richard Malka said in a statement.

“(They) have decided to prosecute, through an emergency proceeding soon to be filed with the Paris Grand Instance Court, the recording and publication of their conversations,” the lawyers said yesterday.

“Protecting the secrecy of private conversations is... one of the founding principles of a democratic society.”

The potential for the affair to damage Sarkozy grew after Marine Le Pen, leader of the anti-immigrant National Front (FN), separately said yesterday that Buisson had a secret meeting with her father Jean-Marie, then FN leader, during the 2007 presidential vote.

Excerpts of the tapes were published this week in satirical weekly Le Canard Enchaine and right-wing news site Atlantico.fr.

Buisson’s lawyer, Gilles-William Goldnadel, said on Tuesday the recordings were authentic. He said his client had made them for historical research purposes and had not intended that they be made public.