Formula 1's small teams say Bernie Ecclestone has floated a plan to boost the F1 grid with 'Super GP2' cars.
During discussions between teams and Ecclestone at the Brazilian Grand Prix, one idea put forward was for a two-tier F1 to be created in the future.
As well as the usual constructors, the grid could be filled with upgraded GP2-type single-make cars, which would be run by customer teams.
Force India deputy team principal Bob Fernley said the idea had been laid out as a possibility, and that it had fuelled fears that Ecclestone wants the smaller teams out.
"There is an alternative, which is 'Super GP2'," said Fernley. "It would be similar to a GP2 car with an upgraded engine.
"The clear direction we are getting is that there is a desire to have five constructor teams and five customer teams, which will be the best way that they [the sport's owners] feel to go."
Sauber team boss Monisha Kaltenborn thinks that the vision of a customer scenario like Super GP2 is worrying because it shows Ecclestone and CVC are looking at a future without smaller outfits.
"Looking at the proposals which have been made, we have to believe that there is some agenda here," she said.
"The agenda seems to be that people are looking at four or five names to remain in here and, when ideas are offered to us of a year-old chassis or engines which maybe are a different spec or whatever, or even a different series, there must be an agenda.
"And since nobody is reacting to it in front we don't know whose agenda it is."
She added that the current atmosphere and the nature of solutions being suggested was making progress tough.
"These things are changing every day. But the fact is it cannot go on like this, it's no way we want to work and can work," said Kaltenborn.
"The more these ideas are coming up, the more we three get the feeling that maybe some people don't want us to be around and maybe the sport is supposed to be changed in a very different way."