Police Scotland is facing a sexism row after an inspector said female firearms officers should not be deployed together if men were available.
In an internal email, obtained by BBC Scotland, the officer acknowledged he may be accused of being sexist.
But while stating the need for a gender balance for searches he also highlights "physical capacity" and the "balance of testosterone perspective".
Police Scotland said the wording of the email was "unacceptable".
The email has also been criticised by a former deputy chief constable as well as Justice Secretary Humza Yousaf.
The revelation comes just two months after two female officers said more needs to be done to tackle sexual inequality and misogyny within Scottish policing.
At the time new Chief Constable Iain Livingstone said any suggestion of a deep-rooted problem was "unfair".
The force currently has 572 Authorised Firearms Officers (AFOs). The vast majority, 539, are male while only 33 (6%) are female.
The email was sent in January by a then temporary inspector, based in the east of the country.
It read: "Im (sic) going to plunge in with both feet and open myself up to being accused of being sexist!
"For operational reasons I don't want to see 2 x female officers deployed together when there are sufficient male staff on duty.
"This is based on my experience in the firearms and routine policing environment, other than the obvious differencies (sic) in physical capacity, it makes more sense from a search, balance of testosterone perspective.
"If you want to discuss my door is open."
It concludes: "Ladies, For the purpose of transparency I have included you in this email.
"Likewise if you want to discuss my door is always open."
Former Tayside Deputy Chief Constable Angela Wilson, one of the officers who openly criticised the force in August, said the email highlighted a serious problem.
Ms Wilson said: "To be quite frankly honest with you it is outrageous, it is disappointing and really you shouldn't see emails like that in this day and age.
"It smacks of being misogynistic, it smacks of being bullying and possibly being discriminatory towards female officers.
"Female officers are trained exactly the same as their male counterparts in firearms so are totally, equally capable of dealing with an incident so it is irrelevant what the crew is made up of."
Ms Wilson said firearms officers go through the same rigorous physical and mental training regardless of their gender.
But she said she was not taken aback by the contents of the email.
She added: "Sadly it doesn't surprise me as I know there are still pockets of people with these types of attitudes.
"I think Police Scotland should be doing more to root out people with these attitudes because it tends to lie at the middle supervisory ranks, not necessarily at the top of the organisation and not necessarily officers coming in at the lower ranks. It's in the middle."
Justice Secretary Humza Yousaf described the language used in the email as "utterly intolerable".
He said: "That is not the kind of language I would expect any police officer, junior or senior in rank, to be using but it will be for the chief constable, undoubtedly, to investigate and we will leave that in his hands.
"He will be of the same opinion as me, I am sure, that that language is just utterly unacceptable."
Jillian Merchant, a solicitor with Thompsons, said: "I think the first thing that comes to mind is that it might be an act of sex discrimination.
"In law discrimination is where someone is treated differently because of their sex and in this situation it does appear that women firearms officers might be being treated differently from their male counterparts."
Police Scotland told the BBC the Code of Practice for Stop and Search states officers cannot search people of the opposite sex.
But Ms Merchant speculated as to how that could be applied as only a small percentage of firearms officers are women.
She added: "That would beg the question that there must be an awful lot of times when there are two male firearms officers on duty and it is not immediately clear why there can be two male officers on duty but not two female officers on duty."
Police Scotland confirmed two former female firearms officers are currently taking legal action against the chief constable on the grounds of discrimination.
Ch Supt Matt Richards, divisional commander for specialist services, said: "The email was dealt with immediately and the matter was investigated fully.
"The officer fully accepts the wording was unacceptable and does not meet our values of fairness, integrity and respect.
"He was spoken to by senior management and issued with corrective advice.
"The officer has apologised and the matter was dealt with internally."
PFOA Trustee Jim Roger is a member of National Womans Armed Policing Forum