Andy Burnham admitted Brits could face more tax hikes to fund his massive social care plan today.

The PM conceded the controversial move to downgrade the 'triple lock' on state pensions might not cover the bill – and suggested the NHS-style care service could take many years to introduce.

He declared that the triple lock – which has seen pensions rise by the highest out of inflation, earnings and 2.5 per cent each year – will go if the party wins the next election. 

That is estimated to cost pensioners £15billion a year by the end of the next decade. 

But economists have warned the move 'won't remotely pay' for the social care plan – even though it would only cover personal care, and some people will still have to sell homes to meet residential costs.

The IFS think-tank pointed out that 'cancelling an unfunded increase does not fee up funds for a new Government commitment'.

Deputy Director Jonathan Cribb said: 'Therefore tax rises or other spending cuts will be needed to pay for social care.' 

The plans for a 'new settlement' on care were unveiled by Mr Burnham as part of his big 'vision' speech at Labour conference yesterday. 

Services would be free at the point of delivery, with a clearly emotional premier saying he wanted to fix the system in tribute to his father Roy, who died earlier this month after a battle with Alzheimer's.

Questions have been raised about whether the announcement is a breach of Labour's manifesto, with ministers admitting they will need to legislate for the change before the next election.  

In a round of interviews following his speech, Mr Burnham acknowledged there could be a 'shortfall' in funding for the National Care Service.

He pledged to be 'honest' about 'where that money is coming from', leaving the door open to tax rises.

The PM told Times Radio: 'I will put a plan before the country at the next general election where we say this is our national care service, 'this is how we will fund it'.'

Mr Burnham added that with a care service, 'the NHS truly will be able to make savings, cashable savings, from a better social care system'.

He continued: 'And then if there's a shortfall, well, we'd have to be honest about that shortfall and say where that money is coming from.'

Mr Burnham also said there was a 'timing question' about when the service would be rolled out.

He told the broadcaster: 'What I've announced at Labour party conference is the big vision – a national care service that can work to NHS principles because then you can have a system that works from home to hospital and back again, a more efficient way of providing care rather than two systems – and the big enabling decision that unlocks a national care service, which is the adjustment to the triple lock.'

The premier said finding funds for the scheme could mean implementation is delayed.

'You could obviously, if you wanted, put the time back, the date back, by which the service comes in,' he said.

'Because the triple lock decision will release the billions, more money will release as we go through the next decade, so there's obviously a timing question there.'

He suggested 2040 would be too late 'because the pressure on the NHS by that point – it's already intolerable'.

Mr Cribb said the savings from altering the pension uprating were highly uncertain, and could be 'anywhere between £4billion and £20billion' a year by 2040. 

The move could 'easily save nothing' by 2034-35, he added - stressing that as the state pension rises were unfunded they could not be used to account for new policy. 

Mr Cribb added: 'To give a sense of scale, if the government wanted to raise around £10billion to spend on social care, it could raise that by increasing the main of VAT by 1 per cent, or add 1 per cent to all rates of income tax.' 

Paul Johnson, former head of IFS, said: 'I think we will have to pay a significant additional amount of tax in order to pay for what is effectively a significant additional leg to the welfare state.' 

Work and Pensions Secretary Pat McFadden told Sky News the triple lock will not end until 2030 - but suggested the Government will pass legislation to axe it before that.

Pressed whether the measure could be passed before the next election, Mr McFadden said: 'Well, we'll legislate before the changes come in.

'We obviously have to do that.'

Asked whether that would 'be a breach of' the 2024 manifesto, Mr McFadden replied: 'No, we're keeping to our promise, which was to maintain the triple lock for the duration of this Parliament.

'And in the future, pensioners should know that their pension will continue to rise every year either by prices or by 2.5 per cent whichever is the greater.

'And there'll also be an additional peg, which is why this is an adjusted triple lock, whereby we will take the proportion of the pension in relation to average earnings in 2030 and lock those gains in for the future.'