Recent reports of major banks in Australia showing massive profits may become an election issue as a senator criticise the big lenders.

Commonwealth Bank today announced the largest annual profit recorded by an Australian bank with its full-year cash profit growing more than 40 per cent to $6.1 billion or almost $700,000 an hour.

Yesterday, National Australia Bank declared $1.1 billion cash earnings in the three months to June, a 22 per cent increase on its profit from the same period last year.

Family First Leader Senator Steve Fielding slammed banks as ''greedy thieves.''

''If Labor and Liberal had any guts they would take on the big banks and make them pay for the years of pain they've caused ordinary Australians by ripping us off time and time again," he said.

The Victorian senator, who is campaigning for re-election at the August 21 poll, labelled the banks as "a bunch of greedy thieves, ripping off Australians trying to live the dream of owning their home."

He said CBA's profit could feed a third world country for a year yet they "get away with sending Australians into mortgage stress because of their unrelenting greed."

At present, Australians owe a record level total of $1.3 trillion in mortgages, credit card and personal loan. The six interest rate hikes since October last year have increased average monthly mortgage repayment costs alone by about $300.