FIA president Max Mosley confirmed in a letter to Formula One teams last week that the new evidence that has led to a fresh hearing over the Ferrari spy saga did come from McLaren's drivers, autosport.com can reveal.
Speculation at Monza ahead of this weekend's Italian Grand Prix pointed towards an email exchange between Fernando Alonso and McLaren tester Pedro de la Rosa that took place shortly after the start of the season.
Sources have revealed that in the emails, de la Rosa makes reference to Ferrari set-up secrets that he had obtained from McLaren's suspended chief designer Mike Coughlan.
It is unclear at this stage who tipped off the FIA about the existence of the email exchange.
McLaren and the FIA have not commented on the nature of the new evidence, but autosport.com can confirm that all F1 teams were informed last week that McLaren drivers had been in possession of 'written evidence relevant to this investigation.'
Mosley wrote to all 11 teams last Friday making it clear that it was their duty to provide any evidence relating to the spy affair.
Similar letters were also sent to Alonso, de la Rosa and Lewis Hamilton, asking them to provide any evidence they had in exchange for an 'amnesty' over any possible sanctions.
Although the FIA has not publicly confirmed or denied that the letter was sent to the teams, autosport.com has obtained a copy from an unidentified source detailing the nature of its latest investigation.
In it, Mosley says the FIA was made aware of: "an allegation that one or more McLaren drivers may be in possession, or that such drivers have recently been in possession, of written evidence relevant to this investigation."
Mosley says it is the FIA's duty to find out if this allegation is true and therefore requires the cooperation of all teams involved to provide documents, and then he drops a big hint about email exchanges.
The letter adds: "In particular (though without limiting the generality of this request) the FIA wishes to receive copies of any electronic communications (howsoever conveyed or stored) which may be relevant to this case and which make reference to Ferrari, Nigel Stepney or any technical or other information coming from, or connected with, either Ferrari or Mr Stepney."
It is understood that Alonso and de la Rosa subsequently provided the information about their email exchange at the start of this week, which prompted the FIA to recall the World Motor Sport Council for a hearing on September 13.