Nicolas Sarkozy’s phone was tapped during a judicial probe into financing for his 2007 election campaign, Le Monde newspaper reported, potentially presenting a new hurdle for the former French president who is widely expected to run for office again.

The newspaper said the phone tapping episode had given rise to suspicions Sarkozy had been secretly advised by a high court judge in exchange for help getting the judge a role in Monaco.

The alleged phone tapping was denounced by Sarkozy’s lawyer, Thierry Herzog, as “monstrous”. Herzog also said there had been “no influence peddling” in the context of contacts with the judge, named by Le Monde as Gilbert Azibert.

A statement from Monaco’s judicial services department confirmed that Azibert had been a candidate for a role as a Monaco high court judge, but said there had been “no outside intervention” in the recruitment procedure.

The statement also said Azibert did not get the job.

The inquiry into election financing began in April 2013, and is still at a stage that remains secret under French legal procedure, precluding any comment from investigating magistrates.

Herzog told the newspaper his long-held belief the ex-president’s telephone conversations were being monitored was reinforced when he learned that the same thing had happened to Sarkozy’s former interior minister, Brice Hortefeux.

“It’s not just scandalous it’s monstrous. It’s a monumental violation of legal defence rights... Mr Sarkozy is probably still being phone-tapped,” he told the newspaper.

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