There is more evidence that last week's federal budget has dealt a blow to consumer confidence.

The Westpac Melbourne Institute Index of Consumer Sentiment fell by 6.8 per cent this month to 92.9, which is its lowest point since August 2011. A reading below 100 points indicates there are more pessimists than optimists on the state of the economy.

"The sharp fall in the index is clearly indicating an unfavourable response to the recent Federal Budget.": Westpac.

The survey was conducted between May 12 and 17 in the days following the budget.