A newly released book has raised the hackles of UBS by claiming that the bank systematically helped French clients evade taxes.

UBS has reacted by threatening legal action against the book’s author, French journalist Antoine Peillon, who claims to have gathered evidence from several former UBS employees.

“Ces 600 milliards qui manquent à la France” (The 600 billion missing from France) claims that UBS trained its staff to target prominent and wealthy French clients and help them evade taxes.

“UBS strongly rejects these false allegations and will defend itself against them vigorously using the appropriate legal means,” the bank said in a statement.

In an interview with the Tages-Anzeiger newspaper on Wednesday, Peillon said that he has a dossier of documents, both hand written and electronic, that support his claims. Among these documents is a list of 120 UBS employees who regularly crossed the border from Switzerland to France.

UBS was fined $780 million by the United States authorities in 2009 after admitting its employees had aided and abetted US clients to evade taxes.

The Swiss government later had to hand over nearly 4,500 names of UBS clients to the US in a move that damaged banking secrecy laws.

The US prosecution was sparked by the testimony of ex-UBS employee Bradley Birkenfeld, who turned whistleblower against his former employer.

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