Ferrari have responded angrily to accusations by McLaren that the Italian team won this year's Australian Grand Prix with an illegal car.
Dennis said the row had damaged the whole of Formula One
McLaren team boss Ron Dennis escalated the spying row between the two teams by making the claim in an open letter to the FIA, Formula One's governing body.
Dennis claimed a 'flexi' floor device, used on race winner Kimi Raikkonen's Ferrari, was illegal.
But Ferrari now say McLaren are making "serious and false accusations".
A statement by the team reads: "Ferrari wishes to state very strongly that its (McLaren's) letter contains accusations that are both serious and false.
"The two cars used in the Australian Grand Prix were deemed by the stewards to be in conformity with the technical regulations before, during and at the end of the event.
We believe the Ferrari press releases, the leaks to the Italian press and recent events have been damaging to Formula One as well as McLaren
"At the next sitting of the FIA International Court of Appeal, Ferrari will fully explain its position on the entire matter."
The spying row blew up when McLaren chief designer Mike Coughlan, who has since been suspended by the team, was found to have nearly 800 pages of Ferrari documents in his house.
Ferrari believe Coughlan received the documents from their now-sacked performance director Nigel Stepney, who says he is innocent of the charges.
The FIA world motorsport council (WMSC) found McLaren guilty of possessing confidential Ferrari information, but said there was "insufficient evidence" that the team had used it to their benefit.
However, a strongly-worded letter from Italian motorsport president Luigi Macaluso to FIA president Max Mosley on Monday led to the latter deciding to send the verdict not to punish McLaren to its court of appeal.
Dennis's 3,000-word letter is addressed to both Macaluso and Mosley.
In it, he initially applauds Stepney for blowing the whistle on his team ahead of the Australian Grand Prix.
Stepney contacted Coughlan, currently suspended as McLaren's chief designer, with regard to two design elements of the Ferrari car he believed to be in breach in FIA regulations.
One - a rear-wing separator - was deemed legal but the other - a 'flexi' floor - was proven to be illegal.
Dennis believes Ferrari ran their cars with the illegal floor at Melbourne and said in the letter: "Ferrari only withdrew the floor device after it was confirmed to be illegal by the FIA.
"Were it not for Mr Stepney drawing this illegal device to the attention of McLaren, and McLaren drawing it to the attention of the FIA, there is every reason to suppose that Ferrari would have continued to race with an illegal car."
Ferrari boss Todt described the verdict as "without logic"
He adds: "It is in the interests of F1 that whistle-blowing is encouraged and not discouraged. If team members think that their identity will be revealed, they will not whistle-blow.
"McLaren's reputation has been unfairly sullied by incorrect press reports from Italy and grossly misleading statements from Ferrari," adds Dennis's letter.
Dennis further clarifies the relationship between Coughlan and Stepney, with the latter alleged to have provided the former with a 780-page Ferrari technical dossier.
Dennis states Coughlan was ordered to break contact with Stepney but they met in Barcelona in April.
Ferrari have suggested McLaren staff were aware of Coughlan's actions, and that they made use of the documents, strenuously rejected by Dennis as "offensive and false allegations".
He concludes: "The reason McLaren was not penalised is that the WMSC rightly concluded that it should not be blamed for Mr Coughlan's actions.
"It based its decision on solid facts and not false innuendo.
"It would be a tragedy if one of the best world championships in years was derailed by the acts of one Ferrari and one McLaren employee acting for their own purposes wholly unconnected with Ferrari or McLaren.
"We believe the Ferrari press releases, the leaks to the Italian press and recent events have been damaging to Formula One as well as McLaren.
"We will naturally present our case before the FIA court of appeal as we strongly believe McLaren has done nothing wrong.
"It is our belief justice will prevail and that McLaren will not be penalised."