Northamptonshire police and fire service to work 'more closely'
Firefighters say they want urgent clarification over whether they might enter into a "partnership" with police.
It comes after Northamptonshire County Council said the police and fire services were looking to work more closely.
Adam Simmonds, the county's police and crime commissioner (PCC), then spoke of a possible "merger".
The county FBU said it had not been consulted on any "blue light partnership" and was seeking answers.
A spokesman for Mr Simmonds said he remained "happy to use the word merger".
"Both services have blue lights and their prime purpose is to protect people and property," he said. "The question is how can they better work together.
"There are discussions taking place with a view to much closer working between police and fire service."
Andre Gonzalez de Savage, the county council's cabinet member for fire and public protection, said: "Closer working between Northamptonshire Fire and Rescue Service and Northamptonshire Police makes very good sense - not just for both organisations, but for the people of Northamptonshire too."
But the county council said there were no details of what that "closer working" might mean.
Sheldon Fenning, chairman of the county's branch of the FBU, said: "We are actively seeking a statement from the fire service whether rumours of a blue light merger or partnership are true or not. We are not at loggerheads with anybody, but we are confused."