Tax on petrol is to rise by 2c a litre from August this year with a corresponding increase in Road User Charges, yesterday's Budget confirms.

The increases were raised as a possibility in July last year by former Transport Minister Steven Joyce after a scheduled 1.5c per litre increase was scrapped due to tight economic conditions.

While there was no confirmation of the increase until yesterday's Budget, AA spokesman Mark Stockdale said it was not a surprise.

"It was deferred from last year and at the time it was suggested it was likely we would have a 2c increase in 2012. So the Budget announcement is in line with what was anticipated to meet inflationary costs in land transport funding."

The petrol excise increase will raise an additional $55 million in the 2012/13 year and a total of $235 million over the first four years.

The increased Road User Charges will raise $38 million extra in year one and $186 million over four years.

Last year Mr Joyce said a further 1.5c a litre increase in petrol excise was likely in the 2013/2014 financial year.