Two NHS boards in Sussex and Surrey are preparing to merge as part of a government savings drive, putting hundreds of jobs at risk, a meeting heard.
NHS Sussex and NHS Surrey Heartlands – two integrated care boards (ICBs) – are expected to have merged by next April, losing many of the 1,350 staff who currently work at the two organisations.
The changes are part of the latest round of NHS reforms which include the abolition of NHS England and the scrapping of independent watchdog Healthwatch.
At a Brighton and Hove City Council meeting on Tuesday, Stephen Lightfoot, chairman of NHS Sussex, said a "significant number" of the boards' staff will not have a job in the coming year.
Mr Lightfoot added: "Over the next three years, when our demand continues to increase, we're going to have to reduce our expenditure.
"We're going to have to work very hard to make better use of the money that we have."
Mr Lightfoot said combining Sussex and Surrey would not affect the overall budget for the two ICBs but was the only safe and reliable way to deliver sustainable services.
He said the ICBs had both been told to halve their running costs by December.
ICBs bring together NHS organisations, councils and others to plan and commission health services in their area, with the aim of improving health and reducing inequalities.
Prime Minister Keir Starmer announced in March that NHS England will be abolished to "cut bureaucracy" and reform how the NHS is run.
Around 9,000 administrative roles are being cut at NHS England and the Department of Health and Social Care as part of the changes - amounting to roughly half of all roles at the two organisations.
