UBS said Martin Liechti, a senior banker who was forced to stay in the US to give evidence in an investigation into a tax evasion probe of UBS, had returned home, according to media reports.

"UBS is pleased to report that Martin Liechti has resolved his status with the US government and returned to Switzerland. Understandably, Martin Liechti plans to spend time with his family and friends," the bank was quoted as saying in a statement.

Mr Liechti, head of UBS Wealth Management Americas, was briefly detained in May by US authorities in connection with probes into whether UBS helped its US clients evade taxes.

In May, the US Department of Justice and the Securities and Exchange Commission revealed they were investigating UBS over offshore services provided by UBS advisors to US clients from 2000 to 2007.

Last month, UBS said it would stop offering offshore Swiss bank accounts through its unregulated units to US customers.