A senior banker at UBS has been held by US authorities investigating whether the bank assisted US citizens evade their domestic tax obligations.

According to the Financial Times the banker is Martin Liechti, who heads up UBS’s wealth management business in North and South America.

It has been reported that his detention took place a month ago while he was visiting Miami from his base in Zurich.

The detention came as part of a US Department of Justice investigation into investment advice UBS allegedly gave US private banking clients from 2000 to 2007.

UBS is reported as saying no employee had been charged with wrongdoing and that the detention took place under a ‘material witness warrant’. There was no confirmation that the employee was Liechti.

UBS yesterday reported a first quarter loss of £5.5bn and redundancies of 5,500 across its operations.