The information emerged on Thursday not in the form of unsubstantiated gossip in the Monza paddock, but a formalised statement to the FIA given by the sacked Renault driver Piquet on July 30.
A signed copy of the document was scanned and published by the website F1SA.com.
Piquet, 23, said he agreed to engineering boss Symonds and manager Briatore's request due to his "fragile and emotional state of mind" and the hope the favour would result in a new contract for 2010.
The Brazilian driver told chief steward Alan Donnelly and investigators from the firm Quest that neither of his bosses discussed the safety of fellow drivers and members of the public, except for Symonds' brief "be careful".
It was reported at the time that the crash, caused Piquet explained in the statement by him accelerating when he should have been braking, resulted in him receiving a blow on the head that he had to have checked by doctors.
He said even his own race engineer did not know about the pre-meditated crash, but that the engineer as well as several journalists had questioned him about the "unusual" incident.