As a US deadline looms, clients of UBS and other foreign banks are urgently seeking advice on whether to reveal offshore accounts to tax authorities or risk prosecution, attorneys say, according to Bloomberg.

A US voluntary disclosure programme, which had been originally due to end in September, has been extended to 15 October.

The disclosure facility allows taxpayers to avoid prosecution and public disclosure of their identities by revealing their accounts and paying back taxes, fines and penalties. More than 3,000 signed up through 21 September, the news agency said.

One of the wealth management firms that has been prominently caught up in the saga is UBS. In February, the Swiss firm agreed to pay $780 million to settle criminal charges it helped wealthy US citizens evade taxes. It has also agreed to hand over names of 250 US clients to the government and in a separate, civil case, it has agreed to disclose a further 4,450 account details.

The news service quoted one lawyer, Robert Katzberg, of Kaplan & Katzberg, as saying: “I’ve got people in complete denial, and people who are panicked out of their mind. There are myriad different human considerations.”

Some clients would rather risk prosecution than pay fines and penalties, Mr Katzberg said. Others choose to disclose their accounts, he added.

The report said that 50 clients approached the New York law firm Kostelanetz & Fink in the past week, attorney Robert Fink said. The firm represents 300 people making voluntary disclosures.