Commonwealth Bank boss Ian Narev says says he is not worried by critics who “take pot shots” at the bank over its financial planning scandal.

The bank chief executive said he takes the scandal, in which at least 1100 Commonwealth customers lost savings due to bad or unethical advice from rogue planners “extremely seriously”.

“Not actually because we’re worried about what people might write or what people are going to say, because there are always going to be individuals who take pot shots at any institution,” Narev said.

“We are worried about it because we let down customers and by letting down you undermine the trust that is so critical to a financial institution.”

Narev said while the “events that led to some of the adverse publicity we’ve had” had been a few years ago the bank realised “how our management of them, and how many years later the actions themselves, can still tarnish the reputation of the institution”.

Narev’s comments to an American Chamber of Commerce lunch in Sydney came after the bank revealed on Sunday that 4,200 concerned customers have so far sought a review of their financial advice under the bank’s Open Advice review program.

Open Advice was set up by the Commonwealth after a damning Senate committee report on unethical dealings by advisers at the bank’s financial planning arm between 2006 and 2010.

The committee called for a royal commission.

The scheme is open for a year for customers to register, with the bank advertising nationally to advise people that the free review is available.

Narev said he did not know how many people would register for a review of their financial advice but the bank’s “instinct” was that most customers in the 2003 to 2012 period covered by the review “got okay advice”.

“Wherever we have done wrong we’re going to put it right,” he said.

Narev said trust in the financial system was critical for a strong economy.

The Commonwealth Bank has already paid $52 million in compensation to affected customers.