By Andrew Benson BBC Chief F1 writer

Ferrari want to establish whether there is enough evidence to lodge a protest that, if successful, could overturn the result of the world championship.

Ferrari are “evaluating footage” that appears to show Red Bull’s Sebastian Vettel making an illegal overtaking move in Sunday’s Brazilian Grand Prix.

Fernando Alonso lost the title by three points to Vettel after finishing second for Ferrari and the German seventh.

Governing body the FIA refused to confirm whether it was investigating.

Red Bull could not be reached.

The footage, from Vettel’s on-board camera, appears to show the German passing Toro Rosso’s Jean-Eric Vergne in a yellow ‘caution’ zone.

If that is the case, and any protest was upheld, it could mean Vettel would have 20 seconds added to his total race time. That would demote him to eighth place and make Alonso world champion by one point.

Alonso has posted a cryptic message on the social networking site Twitter  that appears to be a reference to the situation.

He wrote in Spanish: “I don’t believe in miracles. I make my miracles out of the correct rules.”

Alonso is believed to be pushing Ferrari to make an official protest to the FIA.

However, the governing body does not need a protest from Ferrari to investigate further. In fact, its own rules appear to oblige it to do so.

Article 179b of the international sporting code says: “If, in events forming part of an FIA championship, a new element is discovered, whether or not the stewards of the meeting have already given a ruling, these stewards of the meeting or, failing this, those designated by the FIA must meet… summoning the party or parties concerned to hear any relevant explanations and to judge in the light of the facts and elements brought before them.

It adds: “The period during which an appeal in review may be brought expires on 30 November of the year during which the decision that is liable to review has been handed down, if that decision is likely to have an effect on the result of a championship.”

That appears to give the FIA until Friday to resolve the situation one way or another.

A yellow zone – indicated by yellow flags and flashing trackside yellow lights – indicates that drivers must proceed with caution and overtaking is strictly forbidden.

If a driver is caught overtaking in a yellow-flag zone, the punishment is either to drive through the pits at restricted speed if the race is still under way, or 20 seconds added to a driver’s race time if the incident takes place close to the end of the race or is investigated after the race.

The footage in question was not shown on the main global ‘world feed’ during the race as it was showing repeats of the start at the time.

However, it has since emerged on the video sharing site YouTube after audience members recorded it from extra channels of in-car footage, which was broadcasting from Vettel’s on-board camera at the time.

The video – broadcast on the BBC’s in-car channel – is embedded at the top of this article.

Drivers are also alerted to caution zones by an indicator on their car’s dashboard display as they pass through the relevant area.

If there is any discrepancy between a driver’s dashboard and the trackside indicators, the flags and lights take precedence – the display is meant solely as a further driver aid.

The footage clearly shows Vettel passing a flashing yellow light in Turn Two and another at the exit of Turn Three, after which he overtakes Vergne down the straight, completing the move before reaching a flashing green light, indicating the end of the yellow zone, before Turn Four.

The yellow flag indicator in his cockpit is on the whole time.

The rules dictate that the ‘yellow’ zone ends only when the driver passes the first ‘green’ indicator.

However, on the footage from Vettel’s car it is not possible to see clearly the marshals’ post that is situated on the inside of the track at the exit of the pit lane – after the yellow light at Turn Three.

It is possible that the marshal there was waving a green flag. If he was, the pass on Vergne would be legal and the result would stand.

A green flag is waved at that post as Vettel passes the Marussia of Charles Pic on lap three, but it is not clear whether it was still being waved on lap four.

The likelihood of any protest being lodged or of any action being taken depends on whether Ferrari or the FIA can establish whether there was a green flag waving at that marshals’ post at that time.

If there was, the case will be closed and no further action will be taken. If there was not a green flag, it is highly likely that the case will go before the FIA Court of Appeal.

Under a strict interpretation of the rules, it would seem to have little option in that scenario to impose a penalty. But it may well feel it has to evaluate how much of an effect on the result of the race a drive-through penalty for Vettel at the time would have had.

BBC Sport asked the FIA:

– If the stewards of the Brazilian Grand Prix had investigated the incident in question during the race.

– If there was a green flag waved on lap four at the marshals’ post on the inside of the track after the exit of Turn Three.

– If the FIA was now investigating the incident.

The FIA declined to comment.

For more on this story go to:

http://www.bbc.co.uk/sport/0/formula1/20531638