Schumacher got behind the wheel of a 2007 Ferrari last Friday
Ferrari have hit back at the teams who blocked Michael Schumacher from testing this season's car before his F1 return.
He is set to replace the injured Felipe Massa, but Formula 1 rules prevent on-circuit testing during the season.
In an apparent swipe at Williams, who opposed the move, a Ferrari statement read: "Guess who opposed the test?
"A team that hasn't won anything for years and yet didn't pass over the opportunity to demonstrate once more a lack of spirit of fair play."
Williams, who have not won the world championship since 1997, were backed up by Red Bull and Toro Rosso, who are also opposed to Schumacher getting behind the wheel of Massa's F60 car.
I only have to admit that my neck pinches a bit [in testing]
All three teams argue that seven-time world champion Schumacher, 40, should be treated no differently to Spanish teenager Jaime Alguersuari, who replaced the sacked Sebastien Bourdais at Toro Rosso last month but was unable to track test his car before his F1 debut in Hungary.
"Just for the record, the Scuderia Ferrari had given its approval to let Alguersuari test, but it seems even in this instance someone decided to stick to the precise wording of the regulations," added Ferrari's statement.
Massa fractured his skull during qualifying for the Hungarian Grand Prix after he was struck on the helmet by a spring from Rubens Barrichello's Brawn GP car.
Schumacher is due to replace the Brazilian at the European Grand Prix in Valencia on 23 August, but has only had a chance to drive Ferrari's 2007 car, at the team's Mugello test track last Friday.
McLaren, Renault, Toyota, BMW Sauber and Brawn GP were all prepared to let Schumacher spend one day behind the wheel of the F60.
Schumacher, meanwhile, gave an update on his preparations on his personal website on Wednesday - and revealed that he is suffering slight neck pains as he gets to grips with driving an F1 car again.
"I'm currently in the midst of my preparations for the upcoming race. I already lost three kilograms even if it is also important to me for to build up muscles," he said on www.michael-schumacher.de. "So all in all, the practice is going pretty well.
"I only have to admit that my neck pinches a bit.
"We have to get a grip on that as my health is the priority - that's the clear arrangement made with Ferrari and with my wife too."