The FIA appears to have launched an investigation into Ferrari's fuel system, and is reported to have seized components used by the team at the Brazilian Grand Prix.

According to Auto Motor und Sport's Tobi Grüner, "a thorough investigation of the parts will be conducted in the FIA laboratories.”

It's believed that the seized components include "parts of the fuel system of Ferrari" and in addition parts from "one Ferrari customer and one non-Ferrari".

It comes just after the team had appeared to be given a clean bill of health after being investigated by the governing body as a result of questions raised by rival teams.

Although no official protest was ever lodged, there had been some pointed queries from other teams about how Ferrari had achieved such a big boost in straight line speed since the summer break.

Red Bull suggested three possibilities to the FIA involving increased flow rates and asked whether they would be considered within the rules, which resulted in two technical directives being issued to clarify the situation.

Mercedes boss Toto Wolff told Autosport at the time that: “If somebody was doing what the technical directive clarified, it would have been foul play,”

The officials determined that Ferrari had not in fact broken any of the rules highlighted in Red Bull's enquiry. But even so, doubts have remained over exactly how the Italian team has pulled off its mid-season leap in performance.

Reports that the FIA has seized parts of the fuel system for laboratory testing would constitute a significant escalation of the official enquiry into the SF90.

However it does not appear to have been triggered by a protest - official or otherwise - from another team. Both Red Bull and Mercedes had both said they wouldn't be raising the matter again at this point of the season.

It may be that the FIA simply wants to stamp out once and for all any lingering suggestion of cheating by carrying out its own in-depth and more wide-ranging investigation without waiting for individual specific protests.

After a string of six pole positions from Belgium to Mexico leading to three wins for the team, Ferrari hasn't topped qualifying or won a race since the technical directives were issued.

Sebastian Vettel started from second place in Brazil and Charles Leclerc was fourth fastest in qualifying, but neither driver finished the race after the pair made contact and were forced to retire with six laps remaining.

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