The adviser's taste for the best things in life also reportedly led to him regularly raiding the palace's celebrated wine cellar for fine vintages to accompany working lunches.

Morelle has not contested the accuracy of the shoes revelation and has confirmed Mediapart's claim that the two chauffeurs at his disposal were sometimes tasked with picking up his son from school, citing his "extremely busy schedule".

He had, however, denied the conflict of interest charges.

"As a civil servant, there are a certain number of outside activities which are permitted by the law, including education and advice," Morelle wrote on his Facebook page in response to Mediapart's report.

However, the relevant rules governing such activities require authorisation and the department Morelle worked for said yesterday that it could find no trace of any such authorisation in his case.

Morelle said he was stepping down but denied wrongdoing.

Concerns had also been raised about Morelle's alleged extravagance at the presidential Elysee Palace, at a time when Hollande's government is asking French voters to accept spending cuts to rein in the country's deficit.

Sources close to Prime Minister Manuel Valls said he had met with Morelle yesterday and advised him to resign. The state ethics agency, the High Authority for Transparency in Public Life, said it was launching a "more thorough study" of Morelle's interests and declarations.

The revelations are embarrassing for Hollande, who is struggling with the worst approval ratings of any French leader in modern times.