Stenshorne is 13th in the F3 standings after two rounds and scored his first victory in the sprint race last time out in Australia.
But a GB3 outing at Silverstone on 25-26 April has now had profound consequences on his season, as neither he nor his Hitech team informed the FIA or sought authorisation in advance.
This was therefore viewed as a breach of the strict sporting regulations as it would give him a “sporting advantage” when F3 heads to the British venue in July.
As well as his exclusion, Stenshorne has had four points added to his licence, taking his total to 10 for the rolling 12-month period.
The Norwegian was today announced alongside fellow F3 driver Alex Dunne as the latest recruit to the McLaren development programme, something Stenshorne described as “an honour”.
Explaining the reasoning for the tough sanction, the FIA document read: “The driver of car 15 explained that he was not aware of the requirements of Article 10.4 and that both activities, the test, and his participation in the GB3 event, were organised by his management team.
“The team representative explained that he was unaware of the driver’s participation in the GB3 test and competition in Silverstone until he received the summons from the stewards but admitted that Hitech Pulse-Eight was present in the event as they run three cars in the GB3 Championship.”
It was further outlined that even if Hitech and Stenshorne had requested permission, this would not have been granted “due to the similarities between the GB3 car and the F3 car and the sporting advantage gain for the driver.”
Hitech has issued a statement calling the penalty "extremely harsh" and has appealed the punishment.
A statement read: "Hitech Pulse-Eight notes the stewards' decision relating to Martinius Stenshorne participation in an event outside the FIA Formula 3 Championship.
"The imposed penalty is extremely strong compared to similar infringements. Hitech confirms it has officially appealed the decision.
"Until such time as the appeal has been heard, Hitech will make no further statement. Our focus remains on delivering results this weekend at Imola."
ART's Tsolov has been handed the same penalty and four points on his license, but will miss the Spa round due to competing in a Eurocup event at the track recently.
The British Grand Prix weekend is the fourth-last of the season, with only events at the Hungaroring, Spa Francorchamps and Monza following.
Despite his midfield standing, Stenshorne is only 27 points off early leaders Luke Browning and Leonardo Fornaroli.
With title aspirations of his own after joining the grid as the FRECA runner-up, this punishment only increases what was already an uphill challenge.
