Swan promised sweeping reforms to loosen the grip of Australia's "big four" lenders, slamming the Commonwealth Bank's move to lift borrowing rates above the official 25-basis-point rise.
"The behaviour of the Commonwealth Bank has been arrogant in the extreme," Swan told reporters.
"They have moved in defiance of the analysis of the Reserve Bank (central bank) which says that their debt interest margins have returned to pre-crisis levels."
The comments follow simmering discontent over Australia's comparatively high lending rates, which are set to rise further after the Reserve Bank of Australia moved the official cash rate to up to 4.75 per cent on Tuesday.
Commonwealth Bank responded by putting its rates up 45 basis points, in a move which Swan called a "cynical cash grab". The other big banks have yet to announce rate hikes.
Westpac also reported a mammoth 84 per cent rise in annual profit to $6.34 billion on Wednesday, rounding off a bumper earnings season for the big four.
Commonwealth's earnings are up 20 per cent, ANZ's grew up 53 per cent and the National Australia Bank climbed 63 per cent.
Swan said the global financial crisis had significantly consolidated Australia's banking sector, killing off smaller lenders and putting too much power in the hands of the now "highly profitable" four major banks.
He said reforms would be announced next month to boost regulatory powers and give consumers more freedom and choice, warning the banks not to "underestimate for one moment" how serious he was about shaking up the sector.
"The fact is Australian banks are highly profitable and their net interest margins have returned to levels they were prior to the global financial crisis," he said.
Australia's banks were credited with helping the country stave off recession during the crisis after they eschewed risky lending and investment practices seen in the United States and Europe.
But a series of seven rate hikes since October 2009 has hit home-owners, while thousands of customers are expected to join a potential multi-billion dollar class action against a swathe of unpopular minor banking fees.
"The government is putting in place further reforms to keep the big banks honest, because clearly they have behaved in an arrogant fashion, and clearly what we will do is make the system more competitive," Swan said.
"I think consumers should have a good hard look at their bank and have a look around to see where there may be better options... I think it pays for customers to think about going to another bank," he said.
Swan's statement follows calls from shadow treasurer Joe Hockey to regulate banks' interest rate rises, which was mocked by the government and reportedly criticised by his own party.
Australia was the only major advanced economy to buck recession during the global slump and led the Western world in lifting rates, raising them off 49-year lows with six rapid hikes between October 2009 and May.
Growth surged 1.2 per cent in the three months to June --- the biggest jump in three years -- with unemployment at 5.1 per cent as the country rides a once-in-a-century resources boom on rapacious demand from Asia.
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