Hundreds of public sector jobs could be lost if a possible merger of council and health support services is agreed.

Brighton and Hove City Council, Brighton and Hove Primary Care Trust (PCT), and South Downs Health NHS Trust are considering amalgamating their human resources, finance and payroll departments.

If agreed the merger would affect many hundreds of employees, and their jobs might even be transferred to a private contractor.

Public sector union Unison has expressed "deep concern" after finding out about the plans from a leaked report.

Unison accused the partners of holding "secret meetings" without informing the unions. It has threatened a strike ballot if a formal proposal is ever made.

Alex Knutsen, Unison branch secretary for Brighton and Hove, said: "The branch is deeply concerned at the actions of council and health service officers who appear to have had secret, detailed discussions on a controversial proposal without involving the trade unions.

"Once again the hardworking essential staff who keep frontline services running are being put at risk because of the lack of adequate central Government funding for the council and health trusts.

"Our branch and others will not hesitate to ballot our whole membership should this be necessary to defend public sector jobs and services."

The news comes after The Argus revealed 65 secretarial jobs at Brighton and Sussex University Hospitals NHS Trust might be outsourced to South Africa or India.

Mr Knutsen said: "Due to the secret nature of the talks, and the possibility of privatisation and sending jobs overseas, Unison is being very clear at this moment that our response will be direct and strong.

"I call upon the employers to enter into urgent discussions with the trade unions now and to immediately withdraw any proposal to privatise these services."

He said there were about 300 people just in the city council's human resources, finance and payroll department and there were likely to be hundreds at the health trusts.

Brighton and Hove Unison, which has 3,800 members, has received support from the GMB and other Unison colleagues in health service branches.

A spokeswoman for the council and PCT said they had been working closely on the integration of social care and health services and were having "early discussions".

She said: "We are continually appraising new options for integrating our work where it improves services or reduces costs. When something looks feasible we would engage staff, trade unions and service users at a very early stage.

"At this stage no plans have been made. Staff and trade unions would be fully involved and consulted were any such proposal to be made."

A spokeswoman for Brighton and Sussex University Hospitals NHS Trust said: "We regularly meet our public sector partners, which includes the Brighton and Hove PCT and city council to discuss ways in which services can be improved and made more efficient. In this spirit we are exploring how we might collaborate across organisational boundaries in a number of areas.

"However, there are no plans to merge our finance and human resources departments with these organisations."