McLaren racing director Eric Boullier has insisted he will not resign from his post despite fresh turmoil sweeping through Formula One’s biggest British team.

McLaren’s already troubled season descended into chaos here in France after a whistleblower described the atmosphere at their Woking headquarters as “toxic”, branded the team’s hierarchy as “clueless”, and revealed staff are rewarded with small chocolate bars for their gruelling work.

The management team at McLaren are understood to be furious with the anonymous individual, and Boullier did not rule out detecting and taking disciplinary action against the staff member during an animated press conference.

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Lewis Hamilton, who trails Sebastian Vettel by one championship point, was fastest in both practice sessions as he dominated on F1’s return to France.

But his former team have not won since he left in 2012, and are deep in the midst of their worst run since they started out 52 years ago.

Boullier has presided over their torrid spell after he was hired from Lotus in 2014. On Friday, he attempted to play down the reported turbulence within his team before refusing to take questions over his own future.

A member of McLaren’s public relations department, sitting at the back of the press conference room at the Paul Ricard Circuit, even gestured to the FIA’s head of communications to put a stop to proceedings.

Lewis Hamilton was quickest in practice
Lewis Hamilton was quickest in practice (Tim Goode/PA)

It is understood that McLaren attempted to ease the pressure on Boullier by pulling him from the televised media briefing, and instead draft in their American chief executive Zak Brown.

“I will not resign,” Frenchman Boullier, 44, said. “We are all responsible for the car’s performance.

“I’ve won races and world championships with every team I’ve managed – before and including Formula One – and this is a record you cannot take away from me.”

Boullier’s defence came after a disgruntled McLaren staff member told the Daily Mail: “The atmosphere (at the team) is toxic. We would like to go on strike but people fear for their jobs.

“We have been working all hours of the day, sweating blood, and they give us 25p Freddo chocolate bars.”

Asked if McLaren would take action against the individual, Boullier said: “This is an internal matter which we need to discuss. It is just a couple of grumpy people. We are not where we want to be. We are not happy where we are, but it’s a journey.”

Boullier believes his journey will continue to McLaren’s home race at Silverstone in a fortnight’s time. But even before this week’s troubling revelations, he is believed to be on thin ice.

McLaren won the last of their 20 championships with Hamilton at the wheel in 2008, and have failed to make any progress this season despite their divorce from Honda.

McLaren spent an estimated £60million to sever ties with the Japanese engine supplier and switch to Renault power. Although their star driver Fernando Alonso papered the cracks with a number of promising early-season results, they remain well off the pace.

Alonso was 1.9 seconds slower than Hamilton in practice. His team-mate Stoffel Vandoorne finished 13th.