There has been “no drop in operational standards”, the head of the RAF has said, after its head of recruitment described a policy on diversity as “unlawful”.

Sky News reported last month that a group captain refused to follow an order to prioritise women and ethnic minority candidates.

She told her boss in an email that she was unwilling to allocate slots on Royal Air Force training courses based purely on a specific gender or ethnicity.

Air Chief Marshal Sir Mike Wigston told Sky News on Tuesday there was “absolutely no drop in operational standards, no drop in any standards”.

He said: “There was no discrimination against any group, no standards were dropped, there was no discrimination against any group.

“No approach to recruiting, or any measures that we’ve taken to recruit from the widest pool of talent in the UK workforce, has in any way detracted from our operational standards and our operational service.”

He added: “We’ve been very clear where we stand. We will continue to examine our practices, we will do everything we can to recruit from the widest pool of talent.

“We will be very clear about how we approach any attempts to widen that pool of talent, widen our diversity, and we will continue to protect the nation, we will secure our skies and patrol our seas.”

The MOD has announced it aims to increase the ratio of female recruits coming into the Armed Forces in general to 30% by 2030 from around 12%.

The RAF is aiming to go further. It is seeking for the ratio of female air force recruits to hit 40% by the end of the decade – more than double the current level.

The target for ethnic minorities is to reach 20% of all air force recruits within the same timeframe, up from around 10%.