PARIS (AFP) - France's minister in charge of relations with French-speaking countries is suspected of lying about her assets, a state-appointed transparency watchdog said Monday, referring the case to the courts.

The High Authority for Transparency in Public Life said there was "serious doubt on the... accuracy and sincerity" of Yamina Benguigui's assets declaration last April, when ministers were forced to publicly reveal what they owned following a tax fraud scandal.

But the 59-year-old on Monday denied any "fraud" or "personal enrichment", following weeks of media allegations that she failed to declare shares she held in a Belgian company worth 430,000 euros ($747,000).

"Madame Benguigui's assets are well known and have been regularly declared to the tax administration," her lawyer Martine Malinbaum told AFP.

If the minister is found guilty, she could be sentenced for up to three years in prison, slapped with a 45,000-euro fine and declared ineligible for office for 10 years.

The revelation is a fresh embarrassment for the embattled ruling Socialists, which received a drubbing in municipal polls over the weekend.

Benguigui was elected as councillor for Paris's 10th district in the election, but after the watchdog revelations, Anne Hidalgo, the newly-elected mayor of the French capital, has asked her to resign, sources close to Hidalgo said.

The transparency watchdog was put in place after former budget minister Jerome Cahuzac, in charge of battling tax evasion and fraud, admitted to having a secret foreign bank account last year.

Cahuzac resigned in March 2013 over the scandal.