National Australia Bank (NAB), the country's largest lender, has suspended four traders - including one in the UK - after unauthorised trading in foreign-exchange options triggered a loss of as much as A$180m (€110m), equivalent to 3.2% of NAB's pre-tax profit for 2003.

Immediate action was taken to close out the trading, which took place between October and January and involved the Australian and New Zealand currencies. It is understood that one of those suspended is in NAB's London office, whilst a further two are based in Melbourne, where NAB is headquartered.