Red Bull and Williams are opposed to Ferrari's request to let Michael Schumacher test in Felipe Massa's F60 car as the seven-times world champion prepares to return to Formula One in place of the injured Brazilian.
Formula One regulations do not allow track testing during the season, although Schumacher completed 70 laps in a 2007 version Ferrari at Mugello near Florence last Friday and there has been speculation the sport's bosses may bend the rules given the circumstances.
Red Bull's team principle Christian Horner said on Monday the 40-year-old Schumacher should not be treated any differently to Spanish teenager Jaime Alguersuari who made his F1 debut for Toro Rosso in Hungary last month despite previously only having driven the car in a straight line speed test.
"Jamie Alguersuari had never sat in a Formula One car before his first race last weekend in Hungry. I am sure that Michael Schumacher who is a seven times world champion and has won 91 races won't have a problem getting up to speed," he said.
"Also Michael has driven a two-year-old Ferrari last week in Mugello so I have no doubt that he will be on the pace quickly."
In a statement, Williams chief Frank Williams said the FIA would be setting a precedent if Schumacher is allowed to test.
"While we welcome Michael Schumacher back to Formula One, the fact is that any form of in-season circuit testing is strictly prohibited; a regulation clearly laid out by the FIA and adhered to by all of the teams," Williams said.
"It was for this reason that Alguersuari, who drove an F1 car for the very first time in Hungary, did not have the opportunity to familiarise himself with the Toro Rosso before he made his race debut.
"Williams F1 sees no distinction between Alguersuari's situation and Schumacher's and feels that any deviation from the rule would create a precedent for the future."
So far Williams and Red Bull have received little support from the other teams, with McLaren confirming on Monday they would go along with whatever FOTA (Formula One Teams Association) decides.
German Schumacher came out of retirement after Massa's horrifying accident at the Hungarian Grand Prix last month, which left him with a fractured skull, and is expected to drive for Ferrari at the European Grand Prix in Valencia on August 23.
