The Paris prosecutors office says it is opening a preliminary investigation into allegations that France's budget minister hid money from French tax authorities in offshore accounts.

A statement Tuesday from the prosecutors' office said it also intends to open a probe for defamation based on a complaint over the allegations filed by Budget Minister Jerome Cahuzac.

The online newspaper Mediapart alleged in December that Cahuzac had a secret Swiss bank account until 2010, when the funds were transferred to Singapore.

Cahuzac has led the Socialist government's crackdown on tax evasion - part of a larger effort to bring in funds to cut France's deficit.

A preliminary investigation means the case can ultimately be dropped, or charges filed.

A surgeon by training, Cahuzac served as a lawmaker before his ministerial appointment.