Shorten defiant on banks royal commission

Bill Shorten insists Labor will never give up on having a banking royal commission as the bosses of the big four prepare to front a parliamentary committee.

The opposition leader remained defiant as Commonwealth Bank chief executive Ian Narev prepares to be the first to face the House of Representatives economics committee on Tuesday.

"The only reason that the CEOs of the big banks are attending Canberra to a committee meeting is because Malcolm Turnbull has an absolute obsession about stopping a royal commission," he told reporters in Adelaide on Monday.

"No soft touch, soft ball, whitewash in a parliamentary committee is going to stop a royal commission."

Mr Shorten insists the parliamentary committee won't get to the bottom of scandals that have emerged in the industry or the problem of banks not passing on Reserve Bank rate cuts in full.

Australia's big four banks - ANZ, Commonwealth Bank, National Australia Bank and Westpac - will be grilled by the committee over three days this week.

Prime Minister Malcolm Turnbull in August announced the annual hearing of the banks, similar to the twice-yearly appearances of the Reserve Bank governor, in response to media reports about customers being fleeced.

He defended the hearings on Monday, saying he expected them to go on for many years.

"It's not going to be a one-off hearing," he told reporters in Brisbane.

"This is going to be a very important way of ensuring greater accountability.

"I think it will give the banks the opportunity to explain their position, just as the Reserve Bank of Australia does before that same committee."

Greens finance spokeswoman Sarah Hanson-Young said it was now up to the banks to prove why they shouldn't be subject to a royal commission, given they were raking in massive profits while charging consumers hundreds of millions of dollars in fees.

"It's going to be a big test for them," she told Sky News.