Race stewards of the Fédération Internationale de l'Automobile (FIA) investigating the incident found that Hamilton received instructions to let Trulli pass in the closing stages of last week's race.
Trulli was running on third when he spun off the track, handing over P3 to the trailing Hamilton.
Shortly afterwards, Red Bull's Sebastian Vettel and BMW's Robert Kubica's collided, necessitating a safety car period for the last two laps.
It then appeared that Trulli overtook Hamilton to regain the third position - a prohibited move during the safety card period - all the way to the finish.
In the investigation that followed, Hamilton and McLaren's team manager, David Ryan, said letting Trulli pass and move on to the third spot was not a deliberate decision. Based on their statement, the stewards assumed Trulli had overtaken Hamilton during the safety car period, thus resulting in the Toyota driver's 25-second penalty. He dropped from third to the 12th spot.
In an interview following the race, however, Hamilton said his team told him to let Trulli pass - a statement supported by a recorded radio conversation between members of the McLaren group.
"The stewards, having learned about the radio exchange and the media interview, felt strongly that they had been misled by the driver and his team manager, which led to Jarno Trulli being unfairly penalized and Lews Hamilton gaining third place," the FIA said in a statement.
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