In a study on equal opportunities, Her Majesty's Inspector of Fire Services for Scotland, Neil Morrison, is understood to have said female recruits - whose numbers he is seeking to boost - may be more suitable for support roles like fire investigation or control room duties.

Equal Opportunities Officer for the FBU Linda Shanahan said: "This sounds like a wind-up. It is hard to believe that he would go out of his way to undermine existing women firefighters in this way."

Gender relations expert Professor Gerda Siann, of Dundee University, said that the report was "awful".

"I completely disagree with him. The latest American evidence shows us the spatial ability gap between men and women is disappearing, and the overlap between the sexes is enormous."

The Fire Brigades Union in Scotland wants a central advisory council of Scotland's fire brigades to look into the report.

'Requires spatial skills'

Mr Morrison is reported to have written: "It would seem to be unrealistic to expect equal numbers of females as males to apply to become firefighters, the work of which requires, by its nature, the spatial skills of males rather than the verbal skills of females.

"Recent wide-ranging research into the brain differences of females and males emphasises that males, in using their 'visual right-brain skills', have advantages in solving manipulative and mathematical tasks - for example, setting ladders or positioning vehicles.

"Whereas females, using both hemispheres of their brain, are better with words and at recalling landmarks to find their way over a journey, using verbal skills to tackle visual tests."