Seven-time world champion Sir Lewis Hamilton called for Formula 1 to ensure race officials were “non-biased” as pre-season testing began on Wednesday.
The Mercedes driver, who set the fifth fastest time on day one in Barcelona, said it was “super-essential” for stewards to “have no bias”.
He was speaking as he returned to the track just over two months after losing the title in contentious circumstances.
Sir Lewis also called for there to be “more women in the stewards’ room”.
F1’s governing body, the FIA, has set up a new race-management structure after race director Michael Masi failed to apply the rules correctly in the title-deciding final race.
Masi’s actions were central in the sequence of events that led to Sir Lewis, who had dominated the race before a late safety-car period, losing the lead and the title to Red Bull’s Max Verstappen on the final racing lap after a restart in Abu Dhabi.
Masi has been removed as race director and replaced by two people who will rotate through the role – Eduardo Freitas and Niels Wittich. A beefed-up support structure has also been introduced, including an F1 version of football’s VAR.
At each race, the F1 stewards’ panel features a former driver, to assist the three other stewards.
Sir Lewis said: “Race drivers are sometimes very, very good friends with certain individuals. Some travel with certain individuals and tend to take a more keen liking to some of them.
“So just people who have no bias is super-essential when it comes to making decisions.”
He also said he wanted to see “more women in the stewards’ room”.
“Last year there were maybe one or two. It would be awesome to have a male and female as the two race directors. That’s a great way of promoting diversity.”
An FIA spokesperson said: “The FIA is proud of its global stewarding pathway that connects and develops the most talented stewards from across motor sport.
“This has resulted in a strong, independent and experienced group of officials who carry out their work with impartiality and the utmost professionalism.”
Red Bull team principal Christian Horner said he “wasn’t aware” of any stewards travelling to races, adding: “I don’t think there was any bias from stewards during the last seasons.”
The fastest time on the first day of testing – withcars designed to regulations that amount to the biggest change in F1 for 40 years – was set by McLaren’s Lando Norris.
Lando Norris (GB) McLaren 1:19.568s *
Charles Leclerc (Mon) Ferrari one minute 20.165 seconds
Carlos Sainz (Spa) Ferrari 1:20.416
George Russell (GB) Mercedes 1:20.784
Lewis Hamilton (GB) Mercedes 1:20.929
Sebastian Vettel (Ger) Aston Martin 1:21.276
Yuki Tsunoda (Jpn) Alpha Tauri 1:21.638
Fernando Alonso (Spa) Alpine 1:21.746
Max Verstappen (Ned) Red Bull 1:22.246 **
Valtteri Bottas (Fin) Alfa Romeo 1:22.572s
* denotes C4 compound tyre; ** denotes C2 compound; all other times set on C3 tyre. C1 is hardest, C5 is softest