The bonds, which had an issue price of 7.0 billion francs (S$9.28 billion) and maturity dates between November 2015 and September 2019, now trade at a 'significant discount,' said the bank.

'If the transaction proceeds as expected, it would have a small beneficial effect on UBS's Tier 1 regulatory capital ratio,' added UBS.

The Tier 1 ratio is a measure of a bank's capital strength.

The tender period for the bonds will end on March 25.

UBS is one of the worst-hit banks by the financial crisis. It posted a full year loss of 20.9 billion francs for 2008. -- AFP