The Swiss private banking arm of HSBC has been put under investigation in France.
French magistrates are looking into whether the bank helped some of it clients avoid making tax payments in 2006 and 2007.
Earlier this week it emerged the bank's Swiss private banking arm had been put under investigation for fraud by Belgian authorities.
The allegations included money laundering, criminal organisation and acting as an illegal financial intermediary.
In an emailed statement to Reuters it said:
We confirm that HSBC Private Bank SA (Suisse) SA has been placed under formal investigation by French magistrates who are examining whether the bank acted appropriately between 2006-07 in relation to certain clients of the bank who had French tax reporting requirements, as well as in relation to the way the bank offered its services in the country.
In this context, a guarantee of €50m (£40m) has been demanded of HSBC Private Bank. We will continue to cooperate with the French authorities as much as possible
In its interim results the bank had warned investors that magistrates in Belgium and France were looking into whether its Swiss private banking arm had acted appropriately in relation to some customers with Belgian and French tax report requirements.