Vettel finished fourth in the Spanish Grand Prix, having lost two places to Mercedes' Valtteri Bottas and Max Verstappen's Red Bull after making a pitstop under the VSC.

Vettel admitted making a mistake in stopping his car in his pit on cold tyres that contributed to that loss of position, but he still criticised the VSC system because he feels it contains a weakness in the software that allows drivers to go faster than they should be able to.

"It's the same for everyone but the FIA is supplying us with a system that makes us follow a delta time, and everybody has to slow down by, I think, 40%, but I think everybody's aware you can have a faster way to go under VSC than just follow the delta – by saving distance," Vettel said.

"So, I think we should have a system that hasn't got this loophole, because it forces us to drive ridiculous lines around the track and everybody's doing it so I don't think it's a secret.

"Our sport should be in a better shape than supplying software that's just poor and allows us to find some extra performance that way."

This is the second time Vettel has criticised the FIA's safety car procedure, having described the timing of a real safety car period in April's Chinese GP as "not right".

FIA race director Charlie Whiting said he wasn't aware of any specific problem with the VSC system and disagreed it's possible to manipulate the system by driving a certain way.

"I don't know what he's talking about, honestly," Whiting said. "The VSC has a map in the ECU which is 30% slower than a quick lap. Drivers have to follow that lap.

"It's measured every 50m of travel along the track. It measures where it is relevant to the reference lap and gives you a plus or minus.

"Every 50m they are reminded if they are above or below.

"They are allowed to go negative [quicker than the reference time] but as long as they are positive once in each marshalling sector and at the safety car 1 line [it's OK].

"Even if someone does go slow, as long as they get to zero by that point it doesn't matter.

"If it's measured every 50m then any advantage you can get for taking a different line on the track is going to be absolutely minimal.

"I can sort of see what he's saying, but the racing line is the optimal one."

Additional reporting by Scott Mitchell and Roberto Chinchero