Michael Portillo has mounted a renewed attack on Labour's tax policies, claiming Gordon Brown will be forced to raise taxes in the lifetime of the next parliament.

Speaking on Sunday, the shadow chancellor claimed Labour's record was already one of tax increased. "Under Labour, the tax burden is up by £28 billion. That's equivalent to 10 pence on the basic rate of income tax," he said.

Portillo claimed that the "poorest that have been hit hardest". "The sharpest increase in taxation under Labour has fallen on the 20 per cent of households with the lowest incomes. They now see a larger share of their income going in tax than ever before," he said.

He accused Labour of allowing the state to grow to an unacceptable level.

"When the government spends £12,000 every second, people know that too much money is being wasted. Government has no right to adopt a morally superior tone when it takes money from hard-working people who would have spent it on their families," said Portillo.

Labour was facing a £10 billion black hole in its spending plans, the shadow chancellor claimed.

"Whenever anyone asks Labour whether the £10 billion will come from this tax or that tax, Gordon Brown says that no responsible chancellor could give specific assurances on each and every tax. He says we can't know what unexpected events could arise. The question isn't about unexpected tax increases. The question arises because we know that Labour's spending plans require higher taxes and that Conservative spending plans allow lower taxes," he said.

He stuck to Tory claims that £8 billion in tax cuts was affordable despite claims from Labour that he was, in reality, planning £24 billion in cuts to public services.

Instead, Portillo claimed Labour would be forced to raise national insurance and increase the duty on petrol.

"One way or another, Labour would need to raise £10 billion of taxes. We know there would be National Insurance increases. We expect that petrol tax would go up again. One way or another, there would be more taxes from Labour, leaving less money for the people. Let them now say which taxes they plan to raise," he said.