Brazilian Piquet was asked to deliberately crash to help team-mate Fernando Alonso to win the race.
Nelson Piquet Jr, who was charged with driving the R29, struggled to offer further insight.
The F1 future of Briatore's former charge Piquet Jr is now less certain following his revelations.
Symonds' lawyer Dominique Dumas argued that his client's culpability in Piquet's crash "shouldn't be taken for granted".
The 21-year-old GP2 champion was third fastest behind Renault's Nelson Piquet Jr and Heikki Kovalainen on Thursday.
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Hamilton, along with every other driver in the race other than Renault's Nelson Piquet Jr, chose dry tyres.
Renault, who dismissed Piquet Jr as their driver in August, confirmed they have referred the matter to the British police.
The former world rally champion, who is hoping to succeed FIA president Max Mosely was scathing of Piquet Jr's behavior throughout.
Renault have hit back against the allegations concerning the event made by Piquet Jr in an official statement on their Web site.
Renault are hoping the R29 will allow Alonso and team-mate Nelson Piquet Jr to mount a serious challenge to front-runners McLaren and Ferrari.
Briatore was banned by motorsport's governing body, the FIA, for his part in ordering Nelson Piquet to crash in the 2008 Singapore Grand Prix.
In 1986, Williams had the fastest car but ended up losing the world championship because Nigel Mansell and Nelson Piquet took points off each other.
Piquet explained the incident away at the time that he was trying too hard, made a mistake and scraped one wall a little too closely.
Igual que Senna, Prost o Piquet, tuvo una vida privada reservada.
"His only regret is that he didn't take all the necessary measures when Piquet told him he was going to crash his car into a wall, " Dumas added.
On Tuesday, the Italian saw an FIA ban for his part in Nelson Piquet Jr's deliberate crash at the 2008 Singapore Grand Prix overturned by a civil court.
"I was the one who, when the idea was first suggested to me by Nelson Piquet Jr, should have dismissed it immediately, " he wrote in a letter of mitigation.
It has been claimed that Renault boss, Flavio Briatore, in order to maximize the chances of Fernando Alonso winning the 2008 race, planned the crash of teammate Piquet Jr.
Following Nelson Piquet Jr's dismissal by the team, the Brazilian revealed he had been asked to deliberately crash to help his then Renault team-mate Fernando Alonso win the race.
Ferrari's Massa had been comfortably leading the first-ever night Grand Prix when the safety car was deployed following a crash which saw Renault's Nelson Piquet Jr. hit a trackside wall.
Briatore gave Piquet his chance in F1 after a successful career racing in GP2, but the Brazilian has described his two years at Renault as the worst of his career.
After winning his appeal last week, Briatore told the BBC he had "no involvement at all" in Piquet's deliberate crash and expressed his delight at having his "dignity and freedom back".
Had Ecclestone's proposed system been in place in the past, the team he used to run, Brabham, would not have won the titles they clinched with Nelson Piquet in 1981 and '83.
But Symonds. who has been banned from Formula One for five years, claims driver Nelson Piquet Jr. first hatched the plan to deliberately crash to help teammate Fernando Alonso win the race.
The statement added the three-times former world champion and his son had also attempted to "blackmail the team" into allowing Piquet Jr to continue to drive until the end of the 2009 season.
The team is attempting to restore its reputation in the aftermath of the Singapore incident, which came to light after Piquet Jr. was sacked and then went public with his admission of involvement.
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That's just as well - because they look like needing every drop in the most competitive title run-in since the epic battle between Nigel Mansell, Nelson Piquet and eventual champion Alain Prost in 1986.
There were banners in the crowd imploring both Rubens Barrichello and Nelson Piquet Jr - or Nelsinho, as the locals have it - to crash into Hamilton and force him out of the race.
Nick Heidfeld of BMW took fifth after McLaren's Heikki Kovalainen suffered a puncture with 20 laps to go, with Toyota's Timo Glock and Renault's Nelson Piquet taking the final points positions in seventh and eighth.
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