Patients could find it harder to see their GP because of the rise in national insurance - with 5million a month already unable to do so, health leaders warn.

Doctors say they will be forced to cut back on staff if they are not exempt from the tax grab, which is expected to cost practices around £40,000.

New analysis by the House of Commons Library reveals a quarter of people who contacted their GP surgery in the past month failed to get through on the day they called.

The study, based on an Office for National Statistics survey, showed that 22.4 million people tried to contact their GP in the previous 28 days.

Of these, 5.2 million were unable to get through to their GP on the day that they called, meaning nearly one in four people who wanted to get through to their GP could not.

According to the Library's research, commissioned by the Liberal Democrats, a further 1.2 million people were unsuccessful in contacting their GP at all that month.

The party is joining GPs in demanding the family doctors be made exempt from the employers' national insurance rise, warning that it is a 'tax on community care'.

Dentists, pharmacists, social care providers and charities have also told of their fears that Rachel Reeves' rise from 13.8 per cent to 15 per cent could force them to close.

Helen Morgan, Liberal Democrat's health and social care spokesperson, said: 'Millions of people across the country are already struggling to get a doctor's appointment, now the government's tax hikes risk making the GP crisis even worse.

'This is a tax on community care that will hit GPs, dentists and care homes, making it even harder for them to employ enough staff and deliver the care that local people desperately need.

'Some risk even being forced to close altogether, leaving local patients to pay the price.'

Dennis Reed, director of Silver Voices, which campaigns for elderly patients, said he is 'extremely concerned' the NI increase could make it more difficult to get an appointment.

He added: 'If the government is unable to find the money to reimburse or exempt GPs from these tax rises it could have very serious consequences for patients.

'GP surgeries will be hit with large bills and may have to cut staff, which will make an already bad situation even worse.'

Dr David Wrigley, deputy chair of British Medical Association's GP Committee, said: 'The number of patients struggling to see their GP is disappointing and not surprising due to a significant shortage of GPs on the frontline.

'Over ten years of cuts to public services has left General Practice on its knees.

'The Chancellor's plan to increase employers' National Insurance will place an enormous added burden on practices already operating on the tightest of margins and seeking to remain financially viable.

'If the Government decides to press on by not covering this increased cost for practices as previous governments have done, then this will lead to difficult decisions for practices forcing us to cut back on the services we provide.'

Dr Richard West, whose practice serves 16,000 patients in rural Suffolk, said: 'Our accountants have calculated that the practice will incur additional costs of £140,000 from next April.

'This includes the costs associated with the rise in employers' NICs and the Living Wage. This is equivalent to several senior clinical staff.'

Professor Kamila Hawthorne, chair of the Royal College of GPs, said on Friday that many GP surgeries are 'already struggling to keep their doors open and make ends meet'.

She added: 'For some, this extra financial burden will be the straw that breaks the camel's back, forcing them to make tough decisions on redundancies or even closing their practice, and ultimately it is our patients who will bear the brunt.

A Government spokesperson said: 'We have taken tough decisions to fix the foundations so a £22bn boost for the NHS and social care could be announced at the Budget.

'The employer national insurance rise doesn’t kick in until April, and we will set out further details on allocation of funding for next year in due course.

'We will also hire an extra 1,000 GPs into the NHS by the end of this year, having already announced a contract uplift for GPs and practice staff, and we will ensure practices have the resources they need to offer patients the highest quality care.'