Did Mercedes' James Allison sell out his former team?

The FIA reiterated its firm stance on F1's burning-oil-for-fuel ploy which emerged at the beginning of this year, a move which may have weakened Ferrari.

Engine oil burn suspicions were brought to the forefront earlier this year when Red Bull queried the governing body over the legality of the scheme and suspicions that Mercedes was perhaps getting a boost in qualifying from the trick.

The German outfit quickly denied any wrongdoing however, justifying its speed on Saturday by clever engine mapping.

But ahead of the Azerbaijan Grand Prix, the FIA reminded teams once again of the oil-for-fuel restriction, with pundits believing that Ferrari had been the target of the authority's warning.

"There is someone who is now with the silver team that came from the red team and knew what to look for," said a prominent member of Red Bull Racing, clumsily hinting at Mercedes tech boss James Allison - who worked for Ferrari until the middle of last year - as the person who may have put the FIA on Ferrari's tail.

• We are warriors but we'll always respect Ferrari - Wolff

Renault's Remi Taffin believes that it's likely the FIA had a good reason to repeat its warning in Baku. 

"You never have these kind of discussions and clarifications from the FIA if something hasn't been done," Taffin told Motorsport.com.

"But I have to say that as far as we are concerned, we did not really pay attention to this [last clarification].

"We had much more to do rather than get the last bit out of this kind of things.

"We obviously understand what is being done. We fully appreciate the fact that we need to burn fuel [only].

"I don't think anyone is doing anything like that anymore. Just look at what is out there these days and that is the proper comparison."

GALLERY: F1 drivers' wives and girlfriends

Keep up to date with all the F1 news via Facebook and Twitter