After Westpac's shock announcement yesterday that the bank would nearly double the official rate rise announced by the Reserve Bank, ANZ, NAB and the Commonwealth all resisted the urge to follow suit and said their variable lending rates were ''under review''.

While economists expected an announcement from the remaining three banks yesterday, the fallout and public rebuke from the Treasurer led the others to shelter behind the barrage aimed at Westpac for its bold increase of 0.45 percentage points.

Abuse flowed over Twitter and on-line forums from disgruntled customers. Echoing the sentiment of many, ACT public servant and long-time Westpac customer Dave Headon said he had had a gutful.

Mr Headon and his family will feel the increase more acutely than many, with the family holding Westpac mortgages on three separate properties.

''I feel deeply let down by this move. You've got to ask, if this was three years ago when they were less certain of their position, would they have had the hide, the cheek, to go beyond the RBA rate?'' Mr Headon said.

''We are lucky because we are in a position to absorb this, but many people are not as fortunate as us. Their profits are astronomical, they can't hide behind the claim that they are hard done-by.''

The increase was likely to cost his family several hundred dollars a month extra in their repayments. While he would like to move to another bank, the reality was doing so was difficult and no guarantee of a better deal.

''Unfortunately the whole banking system is one big cartel where things bounce around so much it's simply not practical to shop around.''

Figures issued yesterday by the Australian Finance Group showed despite the increase in interest rates, the average size of a new mortgage in Australia rose to a record high in November. With property prices continuing to increase and investors returning to the market, the nation's biggest mortgage broker said the size of the average home loan rose 6.4per cent to $367,000 the highest level on record in November from last May.

The number of home loan sales fell for the second straight month as first-home buyer activity slowed due to the winding back of government stimulus and the impact of three rate rises in a row, with more expected in the new year.