Sauber and Force India approach FIA with 2017 F1 engine concerns

In April, the World Motor Sport Council ratified a proposal that addressed issues of engine cost, availability of supply, performance convergence and noise.

The cost of an engine supply will be reduced by €1million compared to this year's prices, and that figure will drop by a further €3million from 2018 through to '20.

Similarly, the FIA can compel the manufacturer with the fewest customers to supply a team that needs an engine.

But independent outfits Force India and Sauber do not believe the measures have gone far enough.

As a result, the two teams have written a letter to both FIA president Jean Todt and F1 boss Bernie Ecclestone.

Sauber boss Monisha Kaltenborn and Force India deputy team principal Bob Fernley are also believed to have spoken to Todt and Ecclestone separately regarding the contents of the letter.

Speaking in Monaco, Kaltenborn said: "Force India and Sauber have written a letter to the FIA and the commercial rights holder where we have stated our concerns about the changes.

"It is not up to us to elaborate on it. It's up to those who have the letter.

"Neither Sauber or Force India would have objections if they discuss that with you."