British Transport Police (BTP) has been accused of discrimination after white men were barred from workshops for aspiring applicants.
The events are held to help recruits with their application forms and give them the best chance of success with the subsequent assessment day by staging mock tests.
But sessions held in Manchester, Birmingham and London are only be open to "women and Black/Minority Ethnic groups", it has emerged.
The BTP, which polices railways nationwide, says the restrictions are not discriminatory but instead legal "positive action" designed to boost the number of officers from under-represented minority groups.
But one candidate who wanted the same help given at the workshops – a 48-year-old from Stoke – complained when he was denied a place as he was a white male.
The unnamed man told The Daily Mail: "I am a white heterosexual male. How can a public service blatantly support this kind of discrimination and inequality in 2017?
"It has made me consider withdrawing my application. People should be treated the exact same. This is discrimination.
"I feel it's discrimination to me as a white man. They want to fulfil their quota of a certain person to fulfil their public appearance.
"Candidates should be judged on merit. It should be the best person for the job. Just because I am a white man doesn't mean I can't connect with people from other groups.
"I have a friend who is in the police and when I told him he said they were getting substandard officers through because the BTP is so hell-bent on fulfilling their public image."
The two-hour sessions – advertised as a "Police Officer Application and Assessment Centre Workshop" – include "coaching through the competency based questions, assessment centre preparation, and question and answer sessions".
There is also the chance to meet serving police officers and take part in "practice sessions to complete the ability tests".
A BTP spokesperson confirmed to IBTimes UK the same kind of support was not available to white male applicants.
According to the latest figures, BTP employs 259 black and ethnic minority officers, making up around 10% of its workforce. Of all the police forces in the country, only the Met Police has a higher proportion of BME officers, at 13%.
The BTP wants to increase the proportion to 15%, as well as boost the number of women in senior posts.
Simon Downey, director of capability and resources at BTP, said it is "vitally important" the force "reflects the diverse community that we serve".
He added: "We've carefully studied the reasons why there might be barriers preventing people from these backgrounds applying to the force and are taking steps to help address this.
"These workshops are designed specifically to speak directly to these groups and to increase the number of applications from them, ensuring our force is more representative of the communities who use the rail network.
"Every application we receive will be judged on their individual merits and no one will be discriminated against or favoured because of their ethnicity or gender."