In a New Year's message to staff, Oswald Gruebel said this year heralded a new era of tougher capital requirements although he said the exact impact of such regulations was as yet unclear.

"At UBS, we are well prepared for them - perhaps better prepared than many other banks because we were obliged to change - and have every reason to approach the future with confidence," he is quoted as saying. UBS confirmed the details of the memo to various media outlets.

Revised Basel capital adequacy rules, and moves by the Swiss authorities to tighten capital regulations, have come in as regulators have sought – some may say far too late – to ensure banks have more “buffer capital” to guard against market shocks.

UBS reports full-year results on 8 February. It said it does not expect to pay dividends for some time to come as it uses retained earnings to meet stricter capital regulations.

In November, Gruebel told investors that UBS remained on track to reach a mid-term target for annual pre-tax profit of SFr15 billion francs. In the third quarter, UBS reported net inflows into its wealth management arm, halting successive quarters of outflows that happened amid the bank’s huge credit losses and a bruising clash with US authorities over tax.

"We must ensure that the changes we've made are fully reflected in the results we achieve. We still have a lot of work to do on this front,” his memo said. Gruebel also repeated his commitment to the UBS combination of wealth management, investment banking and asset management. In the past, industry observers had speculated on whether these business divisions would be broken up into separate companies.