Tony Blair used his appearance before a committee of senior MPs to specifically rule out raising the top rate of tax.

In his biannual appearance before the Commons liaison committee, the prime minister was asked whether he agreed with comments by Peter Hyman, a former speechwriter, that a 50 per cent top rate of tax should be introduced for people on higher incomes.

"I am not in favour of raising the top rate of tax," Blair replied.

"Let us be clear, there have been hundreds of thousands of children and almost two million pensioners lifted out of acute hardship, there are people benefiting from the Working Families Tax Credit and from the minimum wage," he said.

"These are big changes. Do we need to do more? Yes we do. That is why you have got to continue the programme of investment and reform but I do not think we should dismiss the progress that is being made."

George Osborne, shadow chief secretary to the Treasury, commented: "Mr Blair appears to have ruled out increasing the top rate of tax. So now he must be honest and tell us which taxes he will raise to pay for his spending plans."

The prime minister also ruled out imposing taxes on cheap flights as electorally impossible.

"Hands up round this table how many politicians facing a potential election in the not too distant future, who would vote to end cheap air travel?" he asked committee members.

Blair also told the committee that details of how British and American troops would hand over control of security in Iraq to the country's own forces could soon be unveiled.

The prime minister added that he hoped the plans for building up Iraq's security forces could follow its recent elections.