McLaren questions Red Bull radio use

The use of team radio to help a drivers' performance was outlawed ahead of the Singapore GP, although advice to help the technical performance or for reliability reasons is still allowed.

McLaren racing director Eric Boullier suggests, however, that Red Bull took things close to the limit with some of its messages to Ricciardo as he suffered battery problems.

F1 teams were explicitly told that instructions relating to contact with kerbs was not allowed, but Red Bull was heard telling Ricciardo: "Avoiding exit kerbs may help the problem with the car."

Speaking about how different dealing with the race from the pit wall was now with the new radio limits, Boullier said: "Nothing, but it makes us more busy listening to the others to see they are not doing anything like Red Bull did twice on Ricciardo.

"I think it was coded, yes. It is up to the FIA to investigate, so it is not for me to say anything.

"But it was a strange message. Once would have been OK, but twice or three times is a bit strange."

Red Bull boss Christian Horner insists, however, that his team had clarified with F1 race director Charlie Whiting whether or not it would be allowed to give the instructions to Ricciardo.

"Obviously we spoke to Charlie and told him Daniel had some reliability issues," he said.

"That was why he was told to stay off the kerbs, because that was causing damage to the battery.

"I think that was sensible and it's about trying to find a balance with this radio ban."