Formula One’s governing body has warned teams it will be keeping a close eye on their fuel systems to ensure none are gaining a performance advantage through clever management of the flow rate.

“With immediate effect we will expect fuel pressure, in the high and low pressure systems, to remain constant above a flow rate of 90kg/hr,” FIA race director Charlie Whiting said in a note issued before yesterday’s Spanish Grand Prix.

“We will also be carrying out careful physical inspections of all fuel systems in use,” he added.

There was no suggestion any teams were doing anything illegal.

However there has been speculation that Mercedes and Ferrari, the two most competitive teams, have been boosting flow rates for short periods of time when it might bring an advantage.

Whiting said the International Automobile Federation did not consider it necessary to define what it considered a “constant” flow but would discuss any concerns with teams “if and when issues arise”.

Ferrari have made a big step up from last season, which was dominated by Mercedes, while Renault-powered Red Bull have struggled with the new V6 turbo hybrid engines.