THE Government’s promise of a £20 billion boost for the NHS will put debt on an “unsustainable upward trajectory” without tax rises or spending cuts to pay for it, the Office for Budget Responsibility has warned.

A fiscal “tightening” totalling around £111 billion in today’s money could be needed in 2023/24 to get debt under control, the official forecaster said.

In its Fiscal Sustainability Report, the OBR said that, without changes to tax and spending policy, public sector net debt could rise from 80% of GDP in 2022 to almost 283% by 2067.

And it dismissed suggestions that the increased NHS spending could be paid for with a “Brexit dividend”, stating that “Brexit is more likely to weaken than strengthen the public finances overall”.

The OBR said: “On current policy we would expect the budget deficit to widen significantly over the long term, putting public sector net debt on a rising trajectory as a share of national income.

“This would not be sustainable.”

And it added: “The main lesson of our analysis is that future governments are likely to have to undertake some additional tightening beyond the fiscal plans in place for the next five years in order to address the fiscal costs of an ageing population and upward pressures on health spending.

“Leaving all or part of the June 2018 health spending announcement unfunded would simply require greater action later.”