Cancer patients in Cheshire could die sooner because they will end up waiting longer for urgent hospital treatment if NHS regulators push through controversial cost-cutting plans, it has been claimed.

Doctors and cancer charities have criticised recommendations by NHS England and NHS Improvement that hospitals in the county cut the amount of endoscopies – internal examinations used to diagnose illness – they undertake by 25%.

Macmillan Cancer Support said the plan was “incredibly worrying for cancer patients”.

It is the latest example of what critics call “draconian” measures NHS care providers in 14 large areas of England are being told to push through as part of its secretive “capped expenditure process” designed to ensure the NHS stays within budget.

An internal NHS document also reveals mental health patients would be hit because regulators have suggested axeing a planned £900,000 boost to the area’s mental health budget for this year, in breach of repeated government pledges of extra funding.

Norman Lamb, the Liberal Democrat health spokesman, said: “That makes a total mockery of the words in the Queen’s speech that mental health should be prioritised by the NHS. It will damage NHS mental health services and disgust families across the country.”

The document, produced by the NHS in central Cheshire on 31 May and seen by the Guardian, lists 24 different “risks” to the care patients receive if the regulators force through their ideas.

Reducing endoscopies by 25% risks patients having to endure longer waits for cancer treatment and also vital diagnostic tests, especially CT and MRI scans and x-rays, it says. It also risks producing a harmful “impact on early diagnosis”, which would set back NHS efforts to tackle poor cancer survival rates through earlier detection.

Dr Fran Woodard, Macmillan’s executive director of policy, said: “Whilst we know difficult decisions are having to be made, it’s absolutely crucial funding pressures don’t cost cancer patients the standard of care they rightly deserve.

“In all cases, the NHS’s sustainability and transformation partnerships process shouldn’t harm cancer care, including getting a rapid diagnosis, accessing timely treatment and appropriate care following treatment. If any of these areas are impacted, countless people may be left anxious or distressed and ultimately this could have an impact on their survival.”

If the Cheshire and Wirral Partnership NHS mental health trust agrees to cancel the extra spending on mental health care, patients would get “inappropriate care” in A&E rather than specialist mental health facilities, the document warns. It would also be a false economy because there will still be “increased spend in hospital care” for such patients. And the trust would have failed to comply with the NHS’s Five Year Forward View blueprint, which promised year-on-year spending increases on mental health care by NHS bodies across England between 2015 and 2020.

The document says the push to keep Cheshire NHS’s overspend in 2017-18 to £3.5m by forcing through such unprecedented measures would result in “significant tradeoffs” that will harm patients and produce longer waiting times. Prescribing fewer and cheaper drugs was also a key part of the plan.

The 21-page paper repeatedly makes clear that cutting costs in these ways could endanger patient safety.

Dr Jeanette Dickson, the vice-president for clinical oncology at the Royal College of Radiologists, said: “While we are yet to see full details of the Cheshire proposals, the identified risk from implementing these cuts is real and undoubtedly will result in the diagnosis of cancer being delayed for some patients.”

Cutting endoscopy services did not make sense, she added. “On one hand GPs are being encouraged to send patients who have a 3% risk of cancer – rather than the previous 10% threshold – on two-week-waiting lists to improve early diagnosis and cure rates, and screening in bowel cancer has been extended to increase early detection.

“However, on the other hand, the primary means by which these early diagnoses will be confirmed – endoscopy – is being significantly reduced. This will have an impact on cancer detection, as well as causing problems for the management of patients who may have benign diseases, but whose symptoms are significantly impacting on their quality of life and employment.”

Labour’s Justin Madders, a shadow health minister and Cheshire MP, said: These plans are a betrayal of the founding principles of the NHS, that access to care should be available to everyone, and also that long waits shouldn’t happen.

“I’m extremely unhappy and angry that such draconian and dangerous proposals are being signed off in secret. Whose authority are these bodies acting on – that of [NHS England chief executive] Simon Stevens or of Jeremy Hunt?”

NHS England and NHS Improvement have decided to impose the plans on 14 areas set to overshoot their savings target this year. In a joint statement, they insisted that singling them out and suggesting such far-reaching savings plans was fair and necessary so that they can balance the books.

“The NHS has to live within the budget that parliament allocates and it is grossly unfair if a small number of areas in effect take more than their fair share at the expense of other people’s hospital services, GP care and mental health clinics elsewhere in the country,” they said.