McLaren chief designer Mike Coughlan "behaved disgracefully" by copying and keeping documents belonging to Formula One rivals Ferrari, London's High Court heard on Tuesday.
The attack came at a hearing to deal with preliminary matters in the Italian team's court case against Coughlan, who has been suspended by Mercedes-powered McLaren, and his wife Trudy.
No details were given in court about how Ferrari allege the Coughlans to have come into possession of the documents at the heart of a 'spying' controversy that has gripped the sport in the last week.
Ferrari lawyer Nigel Tozzi QC told judge Mr Justice John Briggs: "Their conduct by taking these documents, knowing they were not entitled to them, copying them, keeping them -- on any view they have behaved disgracefully.
"We would be blissfully ignorant of all this were it not for a tip-off we received," he added.
Speaking afterwards, Ferrari spokesman Duncan Aldred said the case centred on two computer discs believed to contain a total of 780 pages of Ferrari technical information.
He said Ferrari were not entirely happy with the explanation given by Coughlan about how he came into possession of the material.
This was because of a 'date discrepancy' which the court earlier heard existed between what he had said and date records obtained from a photocopy shop.
Aldred said Ferrari had also asked for access to a computer owned by a third party which Mr Coughlan had used, but that the third party could not be named.
Tozzi argued that the Coughlans should be made to pay the costs, at the highest possible 'indemnity' level, of a search of their house instigated by Ferrari last week, during which their computer hard drives were scanned and documents were recovered.
However, the judge ruled that the Coughlans had "conducted themselves in a highly cooperative and productive manner" during the search and since and should pay some of the costs, to be assessed at the standard level.
The judge also ordered the Coughlans to deliver affidavits to Ferrari by Wednesday morning.
The court heard that the Coughlans lawyers were considering whether doing so would potentially affect their rights to avoid self-incrimination in respect of related proceedings.
Former Ferrari technical manager Nigel Stepney, a fellow-Briton who met Honda boss Nick Fry with Coughlan last month to investigate job opportunities, was dismissed by the team last week and faces legal action in Italy.
The court heard that Ferrari had yet to search through the documents taken, and that the Coughlans have agreed to destroy or remove from their computers anything found by Ferrari.
However, they say that none of the family computers contain such material.
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