Derek Daly, who served as a race steward at the Italian GP, admits they erred when they didn't hand Michael Schumacher a penalty for blocking Lewis Hamilton.
The seven-time World Champion escaped with just a word of caution from Mercedes GP team principal Ross Brawn during Sunday's race after he appeared to make two moves to defend his place against the McLaren driver.
"The FIA were watching it (the incident with Hamilton) and asking us to be careful," Brawn said after the race.
The McLaren camp have expressed their frustration at the lack of punishment for what they described as "pretty harsh" defending from Schumacher and now Daly has admitted the German should have received a drive-through penalty.
'Schumi should have had penalty for blocking in Monza - we blew it - Agh-,' he wrote on Twitter.
Daly has also revealed that he missed the Schumacher-Hamilton incident as he was busy dealing with a different case at the time.
"On lap 20, race director Charlie Whiting asked the stewards to look at an incident between [Felipe] Massa and [Jarno] Trulli at the second chicane," he is quoted as saying by Crash.net. "While looking at the slo-mo video of this incident, I missed the Schumacher-Hamilton incident that happened at that moment.
"When I looked at it again at home, I believe that Schumacher should have been given a drive-through penalty. He was warned repeatedly, and this style of driving is not what you want the future generation of drivers to perfect. We as stewards probably let Charlie down with this one."