Just over 17% of racially aggravated crimes investigated by military police over the past five years resulted in guilty verdicts at court martial, it has emerged, as the armed forces faces new pressure over claims it is failing black and Asian service personnel.

Out of 35 investigations launched by military police over the past five years, only six people have been found guilty, data from a Guardian investigation shows. The Ministry of Defence (MoD) admitted the number of cases investigated by military police services for the army, navy and RAF was already low.

The army’s Royal Military Police (RMP), which carried out 22 of the investigations, referred 13 cases to the Service Prosecuting Authority (SPA), the organisation within the MoD that initiates and conducts prosecutions in criminal cases.

'People like you' still uttered: BAME armed forces personnel on racism in services Read more

However, just six of those army cases ended up being directed to court martial over the past five years, according to statistics revealed under the Freedom of Information (FOI) Act. Of those, four soldiers were found guilty, one was acquitted and another is currently awaiting trial. The other two guilty verdicts across the military as a whole concerned members of the RAF and the navy.

The figures come as the independent ombudsman overseeing complaints in the armed forces warned in December that incidents of racism in the armed forces were happening with “increasing and depressing frequency”.

Emma Norton, head of legal casework at the civil rights group Liberty, told the Guardian: “These stark figures suggest large numbers of BAME service personnel are suffering in silence and feel unable or unsupported to report allegations of racism and pursue complaints.”

“We know from other sources that disproportionate numbers of BAME service personnel have disclosed experiencing bullying, harassment and discrimination. Many service men and women are discouraged from pursuing complaints for fear of harm to their careers.”

She added that the MoD urgently needed to ensure that anyone making complaints was properly supported if racism in the armed forces was to be taken seriously.

Ahmed Al-Nahhas, a solicitor and head of military claims at Bolt Burdon Kemp, said: “The figures really are quite stark and I am afraid that in my practice I have become very cynical about the choices that are made in relation to when matters are referred to the SPA.

“I see a lot of cases involving racial harassment where, for example, there might be an informal chat with a complainant and then attempts are made to try to water down charges.

“I do wonder about the number of cases where, for example, individuals get assaulted but a racial element is not ultimately recorded.”

The MoD failed to provide figures in response to FOI requests for the number of referrals to the SPA by the Royal Naval Police and Royal Air Force Police following investigations into allegations of racially aggravated crimes in the ranks of those services.

However, statistics published online by the MoD for courts martial records that one RAF senior aircraftman was found guilty in 2018 for “using racially aggravated threatening abusive or insulting words or behaviour”. In 2017, a leading hand in the navy was given a £2,000 fine after being charged with racially aggravated harassment.

The degree of punishment in the army has varied. A lance corporal in the Mercian regiment was dismissed in 2017 after being found guilty of “racial aggravated fear or provocation of violence”.

But other cases in that year included a private in the Princess of Wales’s royal regiment who was punished with 90 days’ detention after being found guilty of racially aggravated harassment and using threatening, abusive or provocative behaviour. A trooper in the Household Cavalry was “admonished” after being found guilty of racially aggravated assault.

An MoD spokesperson said: “Racism has no place in the military and anyone found to be behaving in such a way can expect to be disciplined, discharged or dismissed.

“We are committed to stamping it out and have a range of measures to ensure that this issue is tackled.

“This includes creating a new team to deal more quickly and effectively with complaints by service personnel of racism, shifting the culture of the armed forces so that everyone feels included, with even more emphasis on stronger leadership action and improved education and training.”

A report earlier this year by Air Chief Marshal Michael Wigston concluded that the armed forces had unacceptable levels of sexual offences, discrimination and bullying because of a pack mentality among the mostly white, middle-aged men who make up the senior ranks.