SYDNEY (Reuters) - Australia's corporate regulator on Tuesday took aim at the nation's four major banks, saying they are very powerful with "a lot of hubris" and are not used to be taken on by regulators.

Australian Securities and Investment Commission (ASIC) Chairman Greg Medcraft, who was speaking at a Reuters Newsmaker event in Sydney, said he is "not scared of anybody."

Medcraft emphasized the need for bigger penalties for white collar criminals.

"I think they are not being used to taken on," he said.

A 2014 Senate Inquiry stated that ASIC is perceived to be "timid" and "hesitant". It is also seen as weaker compared to Western regulators in terms of the small fines it levies and other penalties it imposes.

ASIC is now trying to rebuild confidence, in part by taking three of Australia's biggest banks - ANZ Banking Group <ANZ.AX>, Westpac Banking Corp <WBC.AX> and National Australia Bank <NAB.AX> - to court after failing to reach a settlement over allegations of benchmark interest rate rigging.

The latest incident to rock Australia's highly profitable "Big Four" banks is potentially the worst, with CBA accused last month by the nation's financial intelligence agency of allowing criminals to launder millions of dollars.

"I think the big banks are extremely powerful in this country," Medcraft said.

"When I became chairman I decided we need to build a war chest to take on big cases...I am not scared of anybody."

Medcraft's tenure at ASIC expires in November.

(Reporting by Swati Pandey; Editing by Shri Navaratnam)