One of the main beneficiaries of a now-banned Formula 1 qualifying engine trick deployed by Mercedes and Red Bull has admitted it was “not so safe”.

It emerged earlier this month that F1’s governing body the FIA has clamped down on a trick Mercedes and Red Bull were using to their advantage during qualifying sessions this year.

To circumnavigate power reduction limits in qualifying, Mercedes and Red Bull had benefitted from a clever loophole by activating an emergency override to immediately cut off their MGU-K for 60 seconds.

While it is understood that the performance gain was minimal, the FIA has since written to teams to confirm the engine trickery would no longer be allowed from the upcoming Miami Grand Prix on 3 May.

Surprise early championship leader Kimi Antonelli conceded having some relief that the trick has been outlawed after it caused some a “stressful moment” during qualifying at the Japanese Grand Prix.

“Obviously, it wasn't the nicest of feelings,” the Mercedes driver told media including Crash.net.

“Of course, we try to squeeze every bit of performance on one side. But it can come with facing some issues or some unexpected situations.

“I was aware that that could have happened, but obviously I didn't really experience it up until obviously Melbourne and Suzuka.

"Obviously, first of all, it's not so safe - especially in Suzuka. I was a sitting duck in the Esses, and knowing that the track is also not very wide, there's not a lot of space.

“It was quite stressful, for sure, not being able to do anything, because obviously the car was not responding to any input. And I just was rolling very slowly on track. It was a stressful moment.”

The Italian teenager, who leads the drivers’ standings by nine points ahead of team-mate George Russell, added: “It’s good to know that obviously, we probably won't face this thing again. 

"Also, in qualifying, you can easily impede someone on a lap, and then you can easily get a penalty. That's not what you want.

“Of course, this comes with giving up maybe a couple of hundredths of a second, so very little time, but at least it gives the confidence that this thing is not going to happen again.”