The mental health trust for Norfolk and Suffolk has been urged to put an immediate halt to its overhaul of services after a union submitted a formal grievance.

Officials from Unison said they had 'grave' concerns about Norfolk and Suffolk NHS Foundation Trust's (NSFT) service strategy, which will result in the organisation reducing its budget by 20pc by 2016.

Union members handed the formal grievance to interim chief executive Andrew Hopkins today, which calls on the NHS trust's board to immediately cease the implementation of its service reorganisation, and agree a clear timetable of negotiation with trade unions.

Fears have been raised about unsafe staffing levels, unmanageable workloads, and union officials said there had been a failure by management to act on concerns raised by staff about the impact on quality and safety of services of the current service changes.

The grievance comes after a survey of 200 NSFT Unison members revealed that 81pc of respondents believed that mental health services were not safe since the start of the redesign and 84pc said they had very low or low confidence in the board of the organisation.

Emma Corlett, NSFT Unison media spokesperson, said the trust needed to evaluate how job losses at the mental health trust had impacted on patient safety, quality of care and the health and wellbeing of staff.

She added that the changes had a 'devastating' impact on staff morale.

'Our members have been raising escalating concerns over a number of months about the impact of the service reorganisation, which the NSFT board have consistently failed to address.'

'Things are now at such a critical point, that immediate action needs to be taken to address current risks to the safety and quality of patient care. Why is that everyone can see the crisis we are in, apart from the people who are paid to take responsibility?' she said.

The mental health trust launched a redesign of services two years ago with proposals to reduce bed numbers by 20pc with more of a focus on community-based care. The shake-up has led to around 400 job losses.

Mr Hopkins, acting chief executive of NSFT, said the letter came as a surprise after working with unions for two years on the service strategy.

'We acknowledge that there are areas of improvement to be made but are disappointed that they have resorted to this approach, rather than engage in discussions with the management of the trust.

'We reject any suggestion that the services we provide are unsafe. We have recently been subject to a review on the risks to quality of our services by KPMG on behalf of Monitor and the Care Quality Commission has completed inspections of a number of our inpatient and community services. While some concerns have been highlighted, which the trust is addressing, these reviews do not paint the picture that Unison is presenting.

'We will carefully consider the points that Unison has raised and will respond in due course.'