The US government is investigating more than 150 US clients of Swiss bank UBS, suspected of being involved in tax evasion, court documents have revealed. Prosecutors gave their first formal indication of criminal investigations into activities of the bank's customers through a filing this week in a Fort Lauderdale federal court. The court filing yesterday came 24 hours before the announcement of the details of a settlement between the US and the bank following a legal dispute over US access to the identities of other clients also suspected of evading tax. The details of about 5,000 account holders are to be handed over to US authorities. UBS has long maintained that handing over client details would be in violation of Swiss bank secrecy laws. So far UBS has admitted to tax fraud in the US and agreed to pay a $780m (£467m) fine along with handing over a limited number of account details as part of a provisional deal to settle the charges. Last week, HM Revenue & Customs signed a deal that will allow it to recover lost tax from Britons holding bank accounts in Liechtenstein. The Alpine jurisdiction has agreed to start exchanging tax information with the UK.