Chief fire officers have criticised the SNP government for failing to provide evidence for a "compelling case" for a single fire and rescue service for Scotland.
The Chief Fire Officers' Association in Scotland has written to community safety minister Fergus Ewing outlining its concerns.
David Wynne, chairman of the body, said: "We are not being critical of fire reform. We are being critical of the government-declared 'compelling case' for one fire service for Scotland.
"There is no strong evidence, or even mild evidence, that underpins a 'compelling case' for a single fire service for Scotland as set out in consultation paper.
"Fire is a complex part of local government services and we fail to understand why fire should be singled out from the wider public sector reform considerations being undertaken by the reform commission."
Mr Wynne said he had not received a reply so far from Mr Ewing. He sent the letter on March 21.
"We really believe that the first stage that a government should take on this matter is defining what sort of fire service they want for the future to meet the challenges of the 21st century," Mr Wynne added.
The consultation on reforming the fire service in Scotland finishes on May 5.
A SNP spokesman said: "No decisions have been taken. Whatever the finally agreed set-up, people across Scotland can be sure of a first class fire and rescue service responsive to local needs.
"That is what people expect from their fire service, and that is what a re-elected SNP Government will deliver."