The future of the NHS can only be guaranteed if politicians commit to huge extra funding, a cross-party group of MPs says.

Writing in the Observer, Sarah Wollaston, Tory chair of the health select committee, Liz Kendall, former Labour shadow health minister, and Norman Lamb, the Liberal Democrat former health minister, say the NHS is too much under threat and too precious to be used as a political football.

Ahead of the 70th anniversary of the NHS in July, they say that if more cash is not committed, patient care will deteriorate as demand rises. “Without a fresh settlement we will face a decade of misery in which the sick, the elderly and the vulnerable will be repeatedly let down. Whatever your politics, that is a shameful prospect for a country with one of the world’s largest economies,” they say.

A report last week by the Institute for Fiscal Studies and the Health Foundation concluded that households would need to pay an extra £2,000 a year in tax to help the NHS cope with the demands of an ageing population. The MPs say a cross-party approach “may seem like blue-sky thinking, given the NHS’s status as the nation’s favourite political football”. But they argue that politicians, health professionals and the public are increasingly aware that tax rises are essential.

Labour will try to keep the pressure on the Tories over the NHS by setting out five tests that health secretary Jeremy Hunt must meet to “bring our NHS back from the brink”. These will included demands that the Tories stop “breaking up and privatising healthcare” and instead integrate services.

The shadow health secretary, Jonathan Ashworth, will call for ministers to apologise for the much-criticised Health and Social Care Act – the flagship reform introduced under the previous coalition by the then health secretary, Andrew Lansley. “The reforms forced on our health service by the Tory-Lib Dem coalition government were the biggest disaster in the proud 70 year history of the NHS,” Ashworth said.

“The Tories were warned that their foolhardy reforms would lead to the fragmentation and privatisation of our public health service, and undermine the integration and coordination necessary to manage the NHS. But they have turned out even worse than anyone could have imagined.”