Image copyright Getty Images Image caption David Cameron, Ed Miliband and Nick Clegg have all made pledges on the NHS in recent days

The NHS and social care services are "at breaking point", a group of leading medical groups and charities have said.

Writing in the Independent, they said the NHS had been through its "longest and most damaging budget squeeze" ever.

The letter says patient care and staff morale have suffered, adding: "Things cannot go on like this."

It is addressed to the leaders of the Conservatives, Labour and the Liberal Democrats - all three parties have made major NHS pledges in recent days.

Leading figures from the British Medical Association, the Royal College of Nursing, the Royal College of Midwives, the Alzheimer's Society, the Teenage Cancer Trust and the Faculty of Public Health are among those who have signed the letter.

'Undervalued and demoralised'

The letter says the coalition government has maintained the health budget in "an era of unprecedented austerity".

"However, historic annual increases in the health budget, designed to keep pace with a growing and ageing population, have been severely reduced - meaning that our NHS has just been through the longest and most damaging budget squeeze in its history," it says.

"Savings have been made, and despite the best efforts of nurses, doctors and other staff, patients have not been insulated from these cuts.

"Too many staff feel undervalued and demoralised when all they want is to be able to care for patients."

The letters says signs of a system "buckling under the twin crises of rising demand and flat-lining budgets are everywhere".

It says these include:

Patients "struggling to get an appointment" due to a shortage of GPs

Many women not getting the "high-quality care they deserve" due to pressures on maternity services

Thousands of patients facing "longer and even unacceptable waits to find out whether or not they have cancer"

Families being "crippled" by the cost of social care, with thousands of elderly and vulnerable people not getting the help they need

People with long-term progressive conditions such as dementia being "cut adrift, reliant on unpaid and unsupported carers"

"The NHS and our social care services are at breaking point and things cannot go on like this," the letter adds.

"An NHS deficit of £30bn is predicted by 2020 - a funding black hole that must be filled."

The letter welcomes that the NHS has "risen to the top of the political agenda" in recent days, with spending commitments for the next Parliament being made at party conferences.

David Cameron promised real-terms increases in NHS spending from 2015-20, Ed Miliband promised an extra £2.5bn a year and Nick Clegg pledged £1bn extra in 2016 and 2017.

But the letter says "a comprehensive, fully-posted, long-term spending plan" is needed to secure the NHS for future generations.