McLaren believe Formula One rivals Renault gained a "clear benefit and unfair advantage" from technical information taken to them by a former employee, according to a memo leaked to the media on Friday.

Renault, the 2005 and 2006 champions, have been summoned to appear before a hearing of the governing body in Monaco on December 6 to answer a charge of unauthorised possession of McLaren information. The team has admitted being in possession of some "old-style floppy discs" that included McLaren engineering drawings and technical spreadsheets but said their cars were untainted by any of their rivals' data.

They have also suspended the former McLaren engineer, Phil Mackereth. However a briefing note, quoted extensively in British newspapers on Friday and also sent to Reuters by a source who demanded anonymity, suggested the information could be far more significant than was initially suspected.

The note said 33 files of McLaren confidential technical information were copied on to 11 floppy discs in March 2006 and then loaded on to Renault's F1 computer system that September. It said that the 33 files contained more than 780 individual drawings "outlining the entire technical blueprint of the 2006 and 2007 McLaren cars." The information was allegedly discussed by up to 18 Renault employees, including seven engineering bosses and heads of department.

"It is clear that McLaren's confidential design information was knowingly, deliberately and widely disseminated and discussed within the Renault F1 design and engineering team, thereby providing them with a clear benefit and unfair advantage," McLaren's lawyers Baker McKenzie were quoted as saying in a dossier submitted to the governing FIA. The source said the lawyers had also complained in writing to Renault's legal team of a "cavalier attitude" on the part of senior Renault F1 personnel during the investigation.

There was no immediate comment from Renault, McLaren or the International Automobile Federation (FIA). McLaren were fined $100 million and stripped of all their constructors' points for 2007 after an extensive dossier of Ferrari [Images] technical information was found in the possession of their chief designer Mike Coughlan.

The Times, referring to a 'concerted attack' by McLaren, saw the leak as an "attempt by the Woking-based team to dispel the impression within the sport that the illegal transfer of technical information from McLaren to Renault is of an altogether lesser order of importance than McLaren's possession of Ferrari secrets."

The latest controversy could have a bearing on the future of double world champion Fernando Alonso [Images], who is expected to return to his former team after splitting with McLaren. The Spaniard may however delay that decision until a ruling on the spying controversy.

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