The Swiss bank has also made lawyers available to the 50-plus bankers involved, many of whom have left UBS since November, when it decided to wind down its cross-border private banking business for US clients, the newspaper said.

The move follows the recent indictment of one of the unit’s former senior executives, Bradley Birkenfeld, who US authorities have accused of helping a billionaire client evade taxes. Mr Birkenfeld has pleaded not guilty. His lawyers and the US government are due to appear before a US judge next Monday.

Earlier in May, WealthBriefing reported the arrest in the US of Mr Birkenfeld.

The arraignment of some 15 pages alleges falsification of Swiss bank documents and the IRS form W8 as well as sales of non-authorised products to US citizens by persons not registered as financial advisors with the SFC.

This follows a reported dispute between Mr Birkenfeld and UBS that began when he refused to sign a document which stated that the risks of his travels to the US to see his clients were to be assumed by himself and escalated into a dispute about severance pay.

UBS is unable to comment on active legal proceedings.