The bank, sometimes called the «millionaires' factory», is facing legal action on several fronts, with a series of claims referred to the corporate regulator last month.

Macquarie Group faces a major class action over allegations some of its investment advisers artificially inflated the price of a small mining company before a sudden collapse wiped out many of its investors.

At a time when its stockbroking arm has only recently emerged from an enforceable undertaking order from the Australian Securities and Investments Commission (ASIC) over its «systemic deficiencies» in compliance with financial services laws, the country's largest investment bank is bracing for another scandal.

Ramping Stock Accusations

The investment bank's brokers are accused of deliberately «ramping» stock in Cleveland Mining Group by playing a key role in the acquisition of a Brazilian iron-ore mine project with a potential value of $34 billion that turned out to be a worthless patch of jungle, according to Australian media reports.

On its website the bank acknowledged the matter but did not comment.