World Endurance Championship chief executive Gerard Neveu has claimed that the decision to schedule the 2016 European Grand Prix on the same weekend as the prestigious 24 Hours of Le Mans race is "a clear attack" by Formula 1.
The provisional itinerary for the next year sees a revivial of the European Grand Prix, which will be staged in the Azerbaijan capital Baku.
However, Neveu has suggested that there is no coincidence that an F1 race is set to run on the same weekend.
"It's a clear attack on us and on this race," Neveu told Autosprint. "[Bernie] Ecclestone never does anything nonchalantly.
"It is a shame because by doing this you take away the possibility of having F1 stars entering what still is the most important race in the world. We could have had Hulkenberg and also other F1 drivers – motorsport fans are losing out.
"The FIA should have protected us better."
Force India driver Nico Hulkenberg won last year's race with Porsche.