ZURICH - SWISS authorities are mulling tougher rules to rein in excessive pay and bonuses at big banks such as UBS , which had to accept a mammoth state aid package after risky US investments threatened its survival.

The historic government intervention to shore up the bank has shocked the nation and sparked a lively debate on whether UBS managers should give back past bonuses, in line with similar calls at other European banks in trouble.

The rescue package for UBS is worth more than 60 billion Swiss francs (S$78 billion), higher than any other Swiss state aid package to date, and has irked some local politicians in the face of the large salaries awarded to the bank's current and past managers.

Justice Minister Eveline Widmer-Schlumpf said over the weekend she wants to strengthen the country's shareholder law to prevent excessive executive pay in the future.

'We must tackle the problem now,' she was quoted as saying in the SonntagsZeitung newspaper.

Broadsheet Blick, the most widely read Swiss newspaper, has launched a campaign to force former UBS Chairman Marcel Ospel to pay back a portion of the 130 million Swiss francs in bonuses he received during his 10-year tenure.

Mr Ospel, whose risky venture into investment banking analysts blame for much of UBS's woes, had to leave his job in haste in the midst of the crisis and was replaced by current chairman Peter Kurer in April.

'Dear Mr Ospel, over the last year you have cashed in at least 44 million (Swiss francs) in bonuses on top of your millionaire pay, allegedly because you did such a good job,' Blick am Sontag said in a letter addressed to the former UBS boss that the paper is encouraging readers to sign.

'Please pay your bonus back.'

PUBLIC APOLOGY

UBS Chairman Peter Kurer had to publicly apologise on Saturday after causing uproar for suggesting two days earlier that top managers at the bank would still get bonuses despite the government rescue package.

UBS shares, held by thousands of Swiss retail investors, have lost about 60 per cent of their value this year.

A poll published by SonntagsZeitung showed that 79 per cent of those interviewed favour the introduction of rules to cap top management pay at 5 million Swiss francs a year.

Mr Eugen Haltiner, chairman of the Swiss banking watchdog EBK, told the NNZ Sonntag paper that he is seeking to introduce a system whereby bonuses would be deferred for some time and paid only if there were no nasty surprises.

'If by the end of the holding time something negative happens, the bonus from the previous years can be further shortened or axed,' he was quoted as saying.