The market watchdog accused both UBS and its French unit that its employees of retail network were unlawfully assisting customers by offering bank accounts overseas to help clients evade French taxes.

ACP, the Bank of France’s regulatory arm, claimed that it had warned the bank about the opening of parallel accounts between 2002 and 2007.

The regulator accused the lender for its lethargic approach of handling such a complex issue and delayed nearly 18 months, when it warned in 2007, to implement corrective measures, in order to resolve this trans-border activity.

Denying the accusations of the regulators in a telephone interview, UBS France deputy chief executive Hervé Mercier-Ythier was quoted by the Wall Street Journal as saying, "It is unfair to accuse us of having covered such operations."

"As early as autumn 2007, the bank reiterated to its employees the obligation to comply fully with law and regulation.

"We had all the checks and balances in place to control cross-border operations, and we have done all these controls," he added.

UBS France can appeal with France’s administrative courts against the fine imposed.