A former UBS employee notorious for providing data associated with a high-profile case against the Swiss bank in the US is now to testify to a French investigation later this month.

A former UBS employee who gained notoriety as a whistleblower on the Swiss bank concerning its alleged assistance to US tax dodgers is to lock horns with his erstwhile firm again by testifying in a French probe on tax issues, media reports said.

Bradley Birkenfeld’s evidence to US authorities played a part in providing the evidence that led to UBS, the world’s largest wealth management house, settling criminal and civil charges against it in 2009, and paying a $780 million sum to as part of the civil settlement. The Swiss authorities, in a historic breach of the Alpine state’s bank secrecy laws, agreed for some client account data to be handed to the US.

Birkenfeld is to give evidence in Paris on February 27, the website Swissinfo.ch reported.

WealthBriefing, sister publication of Family Wealth Reported contacted UBS about the case yesterday but the Zurich-listed lender declined to comment on the matter.

The case comes at a time when controversy about Swiss banks’ activities continues. More than a week ago, a political storm broke out about HSBC’s Geneva-based private bank for its alleged help for tax dodgers, although the bank argues that it has drastically changed operations since 2008.

A number of Swiss private banks, such as Julius Baer, no longer provide offshore banking to US citizens. The last few years since the UBS settlement have also seen the US enacted sweeping – and controversial – tax compliance legislation to catch expats suspected of evading tax.

Reports quoted Zurich-based tax lawyer Milan Patel, stating that Birkenfeld’s testimony could turn up the heat on UBS in France, despite the whistleblower being more closely connected to the US during his time as a client relationship manager at the bank.

“This is a fairly significant development given the fact that Birkenfeld brought down UBS in the US,” Patel was quoted by swissinfo.ch. “He was based in Geneva so he must have had some familiarity with the bank’s cross-border business in France. His focus was on the US but I doubt that this was his exclusive territory.”