The Greens have thrown their support behind Opposition treasury spokesman Joe Hockey's push to rein in the banks.

Mr Hockey's nine-point plan has made headlines for much of the week after he outlined his proposal in a speech on Monday.

Mr Hockey has been ridiculed by the Government over his plan and also copped a lashing from ANZ chief Mike Smith, who accused him of having a personal vendetta against the banks.

Mr Hockey was also forced to deny the details of a damaging leak which alleged his shadow Cabinet colleagues were strongly critical of his actions.

But Greens Leader Bob Brown says his ideas make sense.

"I'm very mindful of the massive profits the banks have announced this week," he said.

"Following the global downturn, alternatives for consumers - for average Australians - have been restricted.

"I think most of those consumers, including small and medium-sized businesses, would welcome a look into the banking industry to see how there can be more diversity, more competition."

Senator Brown says he will seek meetings with Mr Hockey on how the proposals can be progressed.

A Senate inquiry established yesterday will also investigate competition within the banking sector.

Mr Hockey has proposed nine measures to increase competition between the four big banks including giving the Australian Competition and Consumer Commission (ACCC) more powers and a full review of the financial system.

Economic reform

The increased focus on banking competition this week came as the Federal Government and Opposition sought to discredit each other's economic credentials.

Both Prime Minister Julia Gillard and Opposition Leader Tony Abbott have used speeches to accuse the other of ducking serious economic reform.

And the argument continues with the release of assumptions and costings underpinning the Henry review of taxation.

Federal Treasury advice shows it would have cost the Government $500 million to overhaul the personal tax system, including simplifying tax rates.

Mr Hockey says that is a good thing.

"The goal out of tax reform has to be that a government collects less tax and ultimately spends less," he said.

"That's what we want out of our governments - we want less government interference in our lives."

The proposal included simplifying the tax brackets, introducing a standard tax deduction for expenses and changing the fringe benefits tax rules for cars.

The Government released the advice after a sustained campaign by the Coalition.

Opposition finance spokesman Andrew Robb says the document shows the Government is not prepared to make hard decisions.

"The Treasurer ducked any reform before the last election on tax," he said.

"[He] had an opportunity to introduce major and important reform, squibbed it and now the country's all the worse for it."

But Trade Minister Craig Emerson says the Opposition is trying to distract attention away from Mr Hockey's focus on the banks.

"This is just a political convenience at the end of a dreadful week," he said.

Mr Hockey says he is not put off by the criticism.

"We're not backing down one iota - not one iota," he said.

"Mr Smith earns $50,000 a day, but the people who underwrite his bank earn $50,000 a year and they're the people we're concerned about."