Turkish rider Oncu chopped across the front of Gresini’s Jeremy Alcoba on the back straight between Turns 11 and 12 at the Circuit of the Americas.
Alcoba crashed as a result, while the following Snipers Honda of Andrea Migno and championship leader Pedro Acosta on the Ajo KTM clattered into the stricken Gresini Honda.
Both were launched into the air and crashed down heavily, but all three riders walked away unscathed from the incident.
The race was red-flagged, having already been halted on lap eight of the original start for a crash for Filip Salac.
A five-lap restart took place after the Salac incident, but was not restarted following the Oncu incident on lap three – with the results of Sunday’s race taken from the end of the original start before the red flag.
For causing the incident Oncu has been hit with a ban for the upcoming Emilia Romagna and Algarve Grands Prix.
A statement from the stewards read: “On 3 October at 11:46 during the Moto3 Race Part 2 of the Red Bull Grand Prix of the Americas you were found to have caused a crash by swerving into the line of another rider on the straight portion of the track between T11 and T12.
“This contravenes the specific instructions given to all team/competitors by email, and it is considered irresponsible riding causing danger to other competitors.
“It is therefore an infringement of Article 1.2.1.2 of the FIM World Championship Grand Prix Regulations.
“For the above reasons and the deliberate causing this serious incident, the FIM MotoGP Stewards Panel has imposed a suspension from participating in the 2021 Emilia Romagna Grand Prix and the 2021 Algarve Grand Prix.”
Deniz Oncu, Red Bull KTM Tech 3
Photo by: Gold and Goose / Motorsport Images
The Stewards also confirmed no appeal was lodged by the Tech3 team.
This is a significant course of action given safety in junior categories has been in the headlines over the past week again following the death of 15-year-old World Supersport racer Dean Berta Vinales at Jerez last weekend.
Aspar rookie Izan Guevara was declared winner of Sunday’s bizarre COTA race, despite his bike breaking down while he was leading the restarted five-lap sprint.