A US judge has ordered the release on a $12 million bond of an accountant charged with tax evasion in the first prosecution of wealthy US clients of UBS, according to a Reuters report.

Steven Michael Rubinstein, who worked for a company in the yacht-building business, was arrested and charged last week with filing a false tax return by failing to disclose the account he controlled at the Swiss bank, the news agency reported.

Mr Rubinstein agreed to surrender his US and South African passports and to wear an electronic monitoring bracelet for the duration of his release ahead of an arraignment hearing set for 22 April.

US authorities have said there will be other tax evasion prosecutions against US clients of UBS as they wage a legal battle with the Swiss bank to try to force it to give up the names of tens of thousands of US citizens suspected of cheating the US government by concealing accounts abroad.

Tax evasion is not considered a crime in Switzerland, although fraud is regarded as a felony - a distinction that is typically not recognised in countries such as the UK or US.

Mr Rubinstein told Federal Judge Barry Seltzer in a Florida court that his assets included his Boca Raton house, which he valued at up to $6 million dollars, and two condominium apartments valued at around $1 million.