Changing the pay rates of public sector workers, including NHS staff, to reflect regional differences would be an “unworkable, divisive nightmare”, union leaders have warned.

Unison said health workers were already suffering a pay freeze, job and budget cuts as well as huge reorganisation in the wake of the government’s controversial health reforms.

In evidence to be submitted tomorrow to the NHS pay review body, Unison will say: “The current UK-wide pay system, which sets a floor pay rate for the NHS and allows for adjustments in high cost areas or local areas with particular recruitment difficulties has proven itself as a robust, effective pay system that adequately follows geographic variations in the UK labour market.”

The government is pressing ahead with plans to introduce regional pay in the public sector, sparking union warnings of massive wage cuts for employees in some parts of the country.

Unison, which holds its annual health conference in Brighton this week, said the current pay system, Agenda for Change, took many years to develop and implement and was recognised as the tool to deliver fair pay.

Unison’s head of health Christina McAnea said: “The Department of Health’s evidence on regional pay is built on sand. For a government that says it wants to cut paperwork, introducing regional pay would be a massively expensive, bureaucratic nightmare, designed to cause huge disruption and conflict.

“Regional pay would cause skills shortages in so-called low cost areas with nurses, midwives and specialised staff being hard to recruit and retain, hitting the care of patients.

“The government wants to introduce a market ethos into the NHS but most private companies abandoned regional pay scales years ago as divisive and unworkable.

“The NHS is already struggling to find billions in so-called efficiency savings and with no extra money promised to fund higher cost areas, the money would have to come from existing budgets.”

Unison will say in its submission: “Market-facing pay would lead to a reduction in public sector pay in some areas of the UK and further entrench low pay in those areas. Reducing public sector pay will not stimulate economic growth but take demand out of the economy.

“Private sector labour markets do not provide an appropriate framework on which to map NHS pay. Modelling NHS pay on private sector pay outcomes would replicate the private sector’s market failures, distortions and inequalities. These failures have led to rapidly rising income inequality and a gender wage gap.

“The differential between highest and lowest earners and between men and women is larger in the private sector than the public sector. Income inequality has also grown between London and the rest of the country over the last decade.”

A Department of Health spokesman said: “Our evidence shows how more market facing pay could help employers make better use of the NHS pay bill. It makes clear that there is a compelling case for implementing market facing pay for all Agenda for Change staff in England, whether they fulfil a support role, work in administration or work on the front line such as nurses and other clinical staff. The principle of equal pay applies to all staff across the entire country.

“Any recommendations must be implemented in a way that is simple, effective and safe. National organisations like Heath Education England are however in the very early stages of development. We have therefore invited the NHS Pay Review Body to consider how, in the absence of detailed evidence about the appropriate job markets, their recommendations on market facing pay might affect recruitment and retention, including the implications for equal pay in these particular organisations.”