Former Renault F1 team boss Flavio Briatore who has been out of F1 since being sacked as Renault boss for his role in the 2008 Singapore race-fixing scandal, said in an interview with RAI: "There's no relationship [between the drivers] any more.

"It was already very formal between the two - that was very clear last year. But I don't think the relationship can be fixed."

Asked whether he expected either driver to leave at the end of the season, Briatore, a former owner of Queen's Park Rangers football club, replied: "That's for sure."

He added: "Sepang was proof no-one is in charge at Red Bull. Vettel is the boss there. You can't have a team manager also doing the driving.

"Normally the team principal goes on the podium at the first race win of the season.

"Christian didn't even have the strength to get on the podium because they're terrified with a driver in charge instead of the team manager."