Leading medical, care and local authority organisations have warned George Osborne that cuts of 6.2% to public health services in England will cripple vital services such as mental health daycare centres, smoking cessation clinics and contraception services.

They say the cuts, demanded by the chancellor in June and to take effect before next April, will wipe out much of the benefit of promised extra NHS funding.

In a letter to the chancellor, the Academy of Royal Medical Colleges (AoMRC), the Faculty of Public Health, the NHS Confederation, the Local Government Association and seven other organisations say the NHS will have to “pick up the pieces” left by the cuts and deal with the consequences of ill-health that could have been prevented.

They say this in turn will jeopardise any gain from the £8bn increase by 2020 promised to the health service in July’s post-election budget, which follows a £2bn increase this year.

The letter’s signatories represent the professional interests of 220,000 doctors, 300,000 nurses, health service leaders, public health specialists and local authority leaders.

It states: “The Faculty of Public Health’s own analysis suggests the eventual knock-on cost to the NHS could be well in excess of £1bn. By any measure then, the planned move is a false economy. On top of this, many of the services delivered through the public health spend by local authorities fund clinical NHS care. Cutting this funding reduces NHS revenues, so it is misleading to suggest that the NHS budget is being protected.”

The organisations say reversing the cuts and investing in prevention in the upcoming spending review would help the government reduce the wider budget deficit while relieving the pressure on an overburdened NHS by tackling inequalities and improving people’s health and wellbeing.

Dame Sue Bailey, who chairs the AoMRC, said: “These cuts fly in the face of common sense. Not only do they hit the poorest and most vulnerable the hardest, they will also result in untold additional costs to the NHS budget.”

Public health spending should be at the heart of overall health policy, “not something that can be cut at a whim”, Bailey said.

Rob Webster, chief executive of the NHS Confederation, representing bodies that commission, plan and provide NHS services, said: “Open any report from any director of public health in any part of the country and you can see health inequalities and poor health putting pressure on NHS services and blighting lives.”

Other signatories to the letter are the Association of Directors of Public Health, the British Dental Association, the Chartered Institute of Environmental Health, London Councils, the Royal College of Nursing, Solace, representing senior managers in the public sector, and the UK Health Forum.

A government spokesperson, speaking for the Treasury, Department of Health and the Department for Communities and Local Government, said: “We believe in the values of the NHS and the security that comes from a properly funded health service, which is why we will be increasing the NHS budget by £10bn and have backed the NHS’s own plan for the future. We have also made sure that the local authority public health grant in England can only be spent on public health activity.

“Difficult decisions need to be made across government to reduce the deficit and ensure the sustainability of our public services. Local authorities have already set an excellent example of how more can be done for less to provide the best value for the taxpayer and like the rest of the public sector they will have to continue to play their part in fixing the public finances, to ensure we deliver security for working people across the country.”