LONDON - Radio silence, well almost, will be observed at the Marina Bay Street Circuit this weekend. The Singapore Airlines Singapore Grand Prix is the first Formula One race this season to be hit by a controversial clampdown on the use of radio communication.

The International Automobile Federation (FIA) issued a follow-up on Monday to a technical directive sent to teams last week, in which it gave more information about what teams could and could not do during a race weekend.

Banned items on the list, provided to the media by the FIA's Formula One delegate, included "any message that appears to be coded".

Coded messages are like the infamous "multi-21" order issued by Red Bull and Mercedes over the radio during the Malaysian Grand Prix last year, which later emerged as a coded order for drivers "to maintain position".

Teams were told that the use of pit boards for such messages was also banned. Other no-nos were answering a direct technical question over the radio from a driver, such as "am I using the right torque map?", and information about the fuel saving needed.

Messages that will still be allowed include:

- Acknowledgement that a driver message has been heard.

- Gaps to a competitor during a practice session or race.

- Tyre choice at the next pit stop and the number of laps done on a set of tyres in a race.

- Information about a rival's likely race strategy.

The FIA moved to limit radio messages after concern that drivers were getting too much help from the pit wall and engineers.

Formula One's sporting regulations stipulate that "the driver must drive the car alone and unaided" and the stricter interpretation of that rule now effectively limits the amount of assistance from the engineers reacting to real-time data from the car.

Pit to car telemetry that can tweak settings remotely is also banned.

The changes, after 13 of 19 races, have caused some concern about safety implications and the impact on fans, who will now hear less chat between drivers and their teams.

The move could also have an impact on the championship duel between Mercedes team-mates Nico Rosberg and Lewis Hamilton, whose relationship was described yesterday by Mercedes motor sports head Toto Wolff as "like enemies".

Fuel consumption is a key concern this season, with the new V6 turbo hybrid power unit and energy recovery systems replacing the thirstier and louder V8s, and teams have been giving drivers plenty of help in managing this.

"This is a complex and controversial decision which will require a significant effort from the teams to understand how best we can work around it," Wolff said.

He will also need to work around the egos of his feuding drivers as they go head-to-head for this year's F1 world title.

Speaking to BBC Sport, Wolff said of Rosberg and Hamilton: "It has changed from an almost amicable relationship at the beginning to very intense... where it was almost like two enemies competing for the world title.

"Here they go, in the same car, competing against each other for that trophy, and one is going to win and one is going to fail. This is a new experience for them - a difficult experience maybe."

REUTERS