The results were announced yesterday by the Department of Justice, which has helped the Internal Revenue Service in tracking down US citizens using offshore accounts, using allegedly “abusive tax shelters” and other schemes, the DoJ said.

Among other details, the DoJ’s Tax Division has defended “refund suits” against the US representing claims of more than $665 million.

Prosecutors for the Tax Division have obtained 135 convictions and guilty pleas during the 2009 financial year, and its attorneys have taken part in the sentencing of 133 defendants during that year, the DoJ said in a press statement.

The most high-profile tax evasion case last year concerned UBS, the Swiss banking and wealth management giant. In February last year, the bank paid a $780 million fine to settle criminal charges that it helped wealthy US clients evade taxes via offshore accounts, and later in that year, it agreed to transfer up to 4,500 client account details to US authorities as part of a civil lawsuit agreement brokered between the Swiss and US governments.

UBS, as well as fellow Swiss banks Julius Baer and Wegelin, have ceased to provide offshore bank accounts to the US market. Additionally, it has been reported that the IRS is moving closer to launching another tax evasion case against another major foreign bank, although the identity of the bank has yet to be disclosed.