Oliver Letwin has stepped back from a commitment to reduce tax in the event of the Tories winning the next election.

The new shadow chancellor, who damaged the Conservatives' 2001 general election prospects with a gaffe on public spending cuts, said he could give no guarantees that he would cut tax.

But he insisted that the party's instinct was to "reduce the burden of tax over time" providing there was scope to do so.

Interviewed on Tuesday, Letwin said public services and sound public finances would remain the number one priority for a future Conservative administration.

The comments signal a shift in emphasis from the previous approach adopted by Iain Duncan Smith. Whilst the former Tory leader put the tax issue at the centre of the Tories' policy agenda, Michael Howard has expressed reservations about the move.

Confirmation that the shadow chancellor is playing it safe on tax will be seen as evidence that the emphasis is set to shift back to schools, hospitals, crime and transport.

Senior Conservatives say the public still believe issues such as health and education should come before any reduction in income tax.

Speaking to the BBC's Today programme Letwin said there would be "no quick fix on tax" under his chancellorship.

"I cannot give any kind of guarantee of a particular tax cut at a particular time partly because we absolutely have to get structural reform of the public services first," he said.

"And partly because we have no idea what kind of fiscal books, what kind of tax and spending position Gordon Brown is going to leave us with.

"At the moment we know that he has built up a considerable pile of debt, which is of course deferred tax, tax that will have to be raised later."

Letwin's stance mirrors the position adopted by chancellor Gordon Brown prior to the 1997 general election.

The new shadow chancellor, however, is unlikely to follow Brown in committing an incoming Conservative administration to Labour's public spending plans.