New Zealand clients of the big 4 Australian banks filed on Monday a class action suit over charges that the lender have collected from them $800 million in excessive default fees.

Ben Hardwick, lawyer for the law firm Slater & Gordon, said that the Commonwealth Bank, Westpac, ANZ Bank and National Australia Bank charged their clients an average of $15 every time they overdraw their accounts, pay their credit card bill late or write a cheque that bounced. He said the real cost for such services was just a few cents.

"These fees are clearly excessive and we estimate charges totaling up to $1 billion over the past six year. This case is about giving New Zealanders an opportunity to take a stand," The Sydney Morning Herald quoted Mr Hardwick,

He estimated the number of New Zealanders affected by the overcharge at more than one million customers or about one-fourth of New Zealand's 4 million headcount.

The class action lawsuit is considered the largest in New Zealand's history. Borrowers are seeking to claw back what they claimed are excessive penalty payments over the past six years, said lawyer Andrew Hooker on behalf of a trans-Yasman group of legal firms called Fair Play on Fees.

A third trans-Tasman company, Litigation Lending Services, is also part of the New Zealand class action suit.

"We are not saying banks can't charge fees, we are saying that they need to be fair and lawful," Mr Hardwick added.

However, Kirk Hope, head of the New Zealand Bankers Association, insisted that NZ banks are acting within Commerce Commission guidelines. "If a bank was out of line and charging too much, the Commerce Commission would potentially have a look at them," he said.

In Australian, the four banks had also been sued by 170,000 borrowers in another class action lawsuit handled by law firm Maurice Blackburn. Besides the big four, included in the Australian lawsuit are St George, Citi, Bankwest and BankSA.

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