Mark Sampson has admitted the latest allegations of racism against him have taken an emotional toll, with scrutiny of his tenure intensifying as England prepare to begin their World Cup qualification campaign.

The women’s team manager bristled as he was questioned for the first time since the Guardian revealed Drew Spence had contacted the Football Association to claim he had made a racial remark towards her.

Sampson once again asserted his innocence and said he believed the investigation into claims of racism and bullying first made by Eni Aluko had been thorough. That is despite knowledge the original investigation, led by barrister Katharine Newton, failed to speak to many of the protagonists, including Spence.

The Chelsea player, who is mixed race, gave a written statement to Newton last week saying she was left offended by Sampson asking her how many times she had been arrested. The original investigation by Newton cleared the Welshman of any wrongdoing but also failed to speak to any of the other players present when it was claimed he made the remarks to Spence.

“I was aware of the allegations and I’ve responded to them,” Sampson said. “My stance on those allegations is still exactly the same. From my experience of the investigation it was very thorough and that’s all I can say. That process was the process and any questions on it are for the FA. I’m an employee of the organisation.”

England play Russia at Tranmere’s Prenton Park on Tuesday evening, the first obstacle on the road to France 2019. The squad have spent 10 days preparing but mounting allegations of discrimination and bullying against the 34-year-old Sampson have overshadowed their first game since they exited Euro 2017 in the semi-finals.

“I think if anyone put themselves in my position they would feel in a very difficult position, emotionally,” Sampson said. “But I’ve been fully aware we’ve got a big game, against the second seeded team in this group. I’ve worked incredibly hard to prepare these players and the players have done the same. Their work rate, their professionalism has been incredible and they’re prepared for a tough game.”

A tricky encounter, undoubtedly, but Sampson is aware that, for him, much more potentially damaging fixtures are looming. The first is on 17 October when government’s culture, media and sport select committee is expected to summon senior FA executives to explain seemingly gaping holes in the initial investigation.

The MPs could also renew calls for a fresh investigation led by someone other than Newton. Sampson was visibly frustrated with sustained questions about his future but insisted he still had the full support of the England squad.

“It’s never been in doubt in my mind that I had the backing of the players both publicly and privately and the backing of the staff,” he said. “That’s fundamentally what’s crucially important to me. The people I’m working with, the people who know who I am, my character, understand and express their views.”

Sampson insists he dropped Aluko from his squad for performance reasons and not because of any enmity. Jodie Taylor is one player who arguably benefited from Aluko being relegated to the bench at the World Cup in Canada in 2015. She was fast-tracked back from injury, took Aluko’s place up front and has continued to excel, winning the Golden Boot at Euro 2017.

Unprompted, she sprung to Sampson’s defence and insisted the controversy had brought the squad closer together. “I cannot comment on the investigation because I have no idea,” she said. “It is purely what we see in the media. But it is tough on Mark, it is tough on the FA and it is tough on the players.

“If anything it has brought the team closer together. Even under Mark it took me 12 months to get a starting spot but I still have so many positive things to say, because he really has improved my game and it shows how far hard work and effort and good attitude gets you.”