A photo of a couple having sex in a fire engine has sparked outrage and led to an investigation to find the culprits. In the photo which was shared on a swingers’ website, a naked blond woman is seen being pushed against a fire tender’s side while the hand of a man caressed her breasts.

The explicit photo was one of a series of other such images posted on a swinger’s website by someone claiming to be a fireman seeking “fellow swingers”. In the photo, a firefighters’ uniform and equipment can be seen behind the couple. The website address of the Greater Manchester fire service can also be seen on the engine’s door. Fire chiefs in Manchester are trying to discover the couple’s identity and promise to sack the culprits for misuse of brigade equipment if they are firefighters.

One person said: “There is real anger within the fire service that a colleague abused his position by having sex in an engine and used the image on a swingers’ site. From the image, we know at least two people were having sex and another was taking the photo, which means at least three people were probably in a Manchester fire station endorsing this indecent behaviour. It’s not a laughing matter and heads will roll. Images like this don’t help the service.”

The man who shared the photos on the website in search of swingers claims to be “athletic” with tattoos and seeking women aged 18 to 60 for “adult parties, blindfolds, dogging and group sex”. The profile from which the photo was posted claims to be from “6ft 5ins Callum, 27” who is “genuine fire crew.”. The profile photo shows the rear view of a man in full firefighting gear.

A spokeswoman for Greater Manchester Fire Service confirmed an investigation is under way.

She said: “We’ll do everything we can to find out about how this picture was made and who was involved.