The government has been accused of attempting to shut down debate over the future of the National Health Service.

Following the publication of the Derek Wanless's interim report into the NHS, ministers have been accused of seeking to shift the debate onto how much should be spent on the NHS - rather than allowing debate on which system should be used to fund it.

Speaking during Tuesday's pre-Budget report, the chancellor said the public had to debate whether it was willing to pay more to improve the NHS in line with the public's expectations.

The Opposition, however, has accused Brown of pre-judging the report, by closing down discussion on whether an alternative system of funding should be found for the NHS.

Denying that it was seeking to stifle debate, Number 10 said: "What the Wanless report makes clear is that there is a legacy of under-investment in the NHS. There is no cost free option. It's a bit rich to try and accuse anybody of trying to close down debate with the publication of an interim report."

The prime minister's spokesman said that people were free to put forward alternative systems of funding but stressed that Tony Blair believed that "no option is cost free".

Number 10 would not, however, say that the new approach meant that taxes would inevitably have to be increased. "The prime minister absolutely agrees with the chancellor's approach - which is to rule nothing out," said the spokesman.

Speaking earlier in the day, Gordon Brown had declined to rule out future tax rises to fund the government's NHS investment programme.

Whilst he conceded that tax increases would be potentially unpopular, he stressed that they may be necessary if the NHS is to meet the public's expectations.

"Nobody wants tax rises, but there has got to be a debate in this country,'' he said. "Do we want the best health service, the pride of the world, something that we can really depend on for the long term future? We have got to put it on a sustainable, long term footing, and if we want that we have got to look at the evidence."

He stressed that "no decisions have been made", but said that the government would try to create a "national consensus" behind its plans.

"I want all the parties, I want the whole of the country to see the figures, to see what the position is and then we make our choice. And that is a decision we will make over the course of the next year after looking at all the evidence," he told GMTV.

However, the Tories have rejected his call - saying that public money alone will not improve the NHS's ills.

"Labour clearly have learned nothing from the failure of their health policies. All Labour can offer is still more of the policies which have already plunged the NHS into crisis," said the shadow health secretary, Liam Fox.