EMAS is in the second of a three-year investment programme

NHS bosses are recommending it joins together with trusts covering parts of Lincolnshire and Northamptonshire.

Maurice Haslam from Unison has given the plans a cautious welcome but said it is inevitable some jobs will go.

If approval is given, it is understood the expanded service could be running by April 2007.

Mr Haslam said: "It presents and creates a great many challenges and certainly some threats to different sectors within the ambulance service, but it also offers potential opportunities.

"I am sure there are jobs that will have to be shed as a result of the merger and that will obviously be one of our concerns.

"It's a huge geographical spread - we don't actually know where the new headquarters will actually be based or if there are going to be any changes in headquarter staff.

"There are quite a lot of logistical challenges that jump out immediately."

EMAS has covered the counties of Leicestershire, Rutland, Derbyshire and Nottinghamshire since 1999.

If given the go-ahead, it would become one of the largest ambulance services outside London.