Cape Town - Renault are unimpressed with Mercedes' "unfair" contracts with their employees, saying the Brackley squad locks staff into unreasonably lengthy gardening leave.
Over the past year Renault have built up their staff, often signing personnel already in the sport.
However, anyone they've tried to bring over from Mercedes has been forced to take lengthy gardening leave before joining the French manufacturer.
"Red Bull is not too aggressive in the way they are keeping their people, but Mercedes are the most aggressive," Renault managing director Cyril Abiteboul said.
"We signed up a senior person from Mercedes last year, and he is not due to join before 2019 because of the contractual situation.
"The UK is very favourable to protect employees for the benefit of the employer, but that is giving us a bit of a hard time.
"We know it, so we simply have to deal with it.
"Red Bull are not stupid in the way they are protecting their staff. Mercedes have the right to do what they are doing, but I think it is a bit unfair.
"They already have the financial resources but now they are blocking the system by making sure no one can go anywhere.
"It is still a sport and we need to provide a good show and interesting show and that is not what is happening if you are doing that."