UBS got a SFr6 billion ($5.6 billion) cash injection from the government last October in exchange for mandatory convertible notes worth a stake of 9.3 per cent in the bank.

UBS was one of Europe's worst hit banks in the global financial crisis, taking more than $50 billion in write-downs, turning to the government for help and replacing top management. In addition, UBS has been embroiled in a dispute over client details with US tax authorities, and the firm has paid a $780 million fine to settle criminal charges that it helped wealthy US clients evade taxes.

Finance Minister Hans-Rudolf Merz was quoted saying last Friday that the Swiss government would not publicly discuss the issue as it was market-sensitive but said it would take a decision in close cooperation with UBS, financial regulator FINMA and the central bank.