Fernando Alonso has criticised the fact that only some teams and drivers are getting early experience of Pirelli's 2017 tyres.
This week, championship contenders Nico Rosberg and Lewis Hamilton are heading to Barcelona, where they will try next year's slicks fitted to a Mercedes test mule based on the 2015 car.
According to Bild, the silver-clad drivers were not keen on the test, but Mercedes's team chairman said: "The race drivers are the fastest and so they can help Pirelli in ways that others cannot."
The other two teams helping Pirelli with their 2017 testing are Ferrari and Red Bull.
Other drivers, however, like Alonso, are not getting the same opportunity, even though McLaren-Honda said at the time that it actually preferred to sit out the Pirelli running.
However, AS claims that McLaren-Honda were never considered an option for the Pirelli running, given Honda's engine problems of last year.
Alonso said: "It is not logical that some teams can test the new tyres and some cannot, but that's what is happening.
"I think everyone should have the opportunity to test the compounds."
The 2016 championship continues on October 23 with the United States Grand Prix.
