Lawyers will be closely watching the Australian Prudential Regulation Authority’s investigation into the Commonwealth Bank to improve their chances in what could turn into the biggest shareholder class action Australia has seen.

APRA on Friday announced that three senior business and regulatory figures would head the inquiry: former ACCC chief Graeme Samuel, businesswoman and former Reserve Bank board member Jillian Broadbent and former APRA chair John Laker.

The inquiry is a groundbreaking move, being the first time the regulator has brought in outsiders to head its investigations and the first time it has announced an investigation into a financial institution and committed to publicly release the results.

“We will watch the Austrac proceedings, the APRA inquiry and the ASIC investigation with interest,” Maurice Blackburn’s class action chief Andrew Watson said.

The firm is currently signing up CBA shareholders for a class action it claims could be the country’s largest, eclipsing the $200 million settlement achieved by shareholder in Centro Properties after its GFC bust.

The firm expects to lodge its action within weeks and while the reports of the APRA inquiry could help with the case “based on what we already know, including CBAs own statements, we think there is a compelling case which we intend to pursue in any event”, Mr Watson said.

CBA is the target of investigations by regulators ASIC and AUSTRAC over its latest scandal, over 54,000 breaches of regulations on money laundering and terrorism funding reporting.

APRA has cast the net much wider. The regulator said on Friday its move involves “a number of issues which have raised concerns regarding the frameworks and practices in relation to the governance, culture and accountability within the CBA group, and have damaged the bank’s reputation and public standing”.

It expects to take seven months to investigate the bank but will issue two public reports, the first will be on January 31 and another on April 30. The latter report will include recommendations of action.

The APRA inquiry has been likened to a Royal Commission into one bank, with Prime Minister Malcolm Turnbull saying it would achieve the same end in a shorter time.

“Now if you had a royal commission into the banks, as Mr [Bill] Shorten proposes, it would take years, you would be flat out getting an outcome within three years,” Mr Turnbull said last week.

However the powers of the inquiry are very different to a Commission. APRA does not have power to compel witnesses to appear, especially those from outside the bank and it will not be conducted in an inquisitorial way with lawyers acting for parties involved. However CBA has said it will fully co-operate with the inquiry.

That means the inquiry will effectively be able to speak to whomever it chooses from within the bank.

While the inquiry is a first in being public and announced, there are some precedents. In 2004 NAB chose to release the results of an APRA inquiry into a foreign exchange scandal that saw the bank lose $360 million in unauthorised transactions.

The fallout saw CEO Frank Cicutto and chairman Charles Allen resign, eight bank staff lose their jobs and one trader being jailed.