The controversy over V10 engines in Formula One looks likely to continue into next year after Red Bull boss Dietrich Mateschitz suggested that his Scuderia Toro Rosso team were unlikely to change to V8 power-units before 2008.
Toro Rosso have been on the receiving end of growing criticism from rival teams about the performance of their V10 engines, which some believe have an advantage over V8s.
Autosport.com revealed at the Australian Grand Prix that Super Aguri and Midland F1 had written to the FIA asking for Toro Rosso to be excluded from scoring points in the constructors' championship because of the engine situation.
A further letter of support from a number of other teams is expected to follow in the next week - with growing anger that Toro Rosso may be gaining from a rule-exemption that was only voted through to keep Minardi afloat.
Mateschitz has said, however, that he is unimpressed with the complaints from rival teams - and especially suggestions that his company should easily be able to fund Toro Rosso's switch to V8s.
"That is absurd," he said, when asked about claims that Red Bull should fork out for a supply of V8 engines. "We simply were the successors of Minardi and there was no other way than to take over the current contracts, including the V10 with Cosworth.
"I would rather today than tomorrow switch to a V8, but it is simply not possible.
For me, it has been proven that the air restriction and the rev limit of the V10 work. But some teams have to get used to the idea that Toro Rosso is not Minardi. You cannot expect this team to be backmarkers forever."
When asked whether his comments meant the plan was for Toro Rosso to continue with V10 engines, he said: "Yes, we have a contract in place until the end of 2007.
"If we alter that into a V8 contract, we have to make sure with Cosworth boss Kevin Kalkhoven that we would get equal treatment to Williams."
The letter from teams that is due to be sent to the FIA before the San Marino Grand Prix is understood to request that the FIA further restrict the performance of V10s in a bid to encourage Toro Rosso to switch to V8s.
The FIA has always said that it will change the rev-limit or air restrictor size of the V10 if it felt the performance of the older engines needed pegging back.