The drivers were penalised for an offence related to the way the clutch of the cars operated during the wet standing start, which was deemed to have potentially mimicked traction control in the tricky conditions.

The penalty - equivalent to an in-race stop-and-go - was the same as that which which be given for a false start.

Alfa boss Fred Vasseur has confirmed to Motorsport.com that the team has already submitted a notification of intention to appeal. It now has 96 hours to decide whether or not to pursue the appeal.

The Alfa drivers had finished seventh and eighth on the road, and they have now dropped down to 12th and 13th respectively.

Their places now go to Haas drivers Romain Grosjean and Kevin Magnussen, while championship leader Lewis Hamilton and Robert Kubica move into the top 10 – with the latter earning the first point for Williams in 2019.

The Alfa cars were reported to the stewards by FIA technical delegate Jo Bauer soon after the chequered flag after their race start data was found to not be in compliance.

A later summons clarified that the cars were under investigation for “alleged breach of Article 27.1, as related to clutch torque application during race starts". Article 27.1 says that that “the driver must drive the car alone and unaided.”

The summons added that in addition to that alleged sporting regulation breach the team was also being investigated under Article 9.3 of the technical regulations, which relates to traction control.

It says: “No car may be equipped with a system or device which is capable of preventing the driven wheels from spinning under power or of compensating for excessive torque demand by the driver. Any device or system which notifies the driver of the onset of wheel spin is not permitted.”

In their verdict, the stewards noted: “The clutch is controlled electronically via the Common ECU. However, the teams have the option to tune some of the controlling parameters.

"In order to prevent the teams from using this tuning to affect the way in which the clutch engages at the start of the race in a way that could potentially mimic traction control or other advantageous schemes, the FIA requires that the torque in the clutch matches (within specified limits) the torque demand as the driver releases the clutch. This must occur within 70 milliseconds.

“In the case of both cars of Alfa Romeo Racing, the time that it took for the torque to align with the torque demand was close to 200 milliseconds [for Raikkonen] and 300 milliseconds [for Giovinazzi] respectively. This provided a more gradual application of the torque, which given the wet conditions was a potential advantage. Regardless of whether there was an actual advantage, the Stewards determined that this was a clear breach of the guidance given to the teams as to how this would be adjudicated.

“The Stewards held a hearing and reviewed the data, with three members of the team present, including the engineers concerned, along with the FIA Technical Delegate and his assistants responsible for these checks. The team accepted that they were not within the required limits.

“The Stewards accepted the team’s explanation that the cause of this was that they were caught out by the unusual weather conditions and the fact that they did not do any practice starts under these climatic conditions and set the parameters in a way that failed to meet the requirements.

“However, the Stewards noted that the FIA Technical Delegates check this parameter on all cars, and that no other irregularities were found. The obligation to meet the requirements is irrespective of the climatic conditions. Therefore, the Stewards considered that a Breach of Article 27.1 occurred.”