West Ham co-owner David Sullivan attended the club's home Carabao Cup win against Portsmouth on Saturday against the advice of the London Stadium's landlord following allegations of sexual misconduct.
Sullivan was accused of sexually exploitative and predatory behaviour by seven women during a joint investigation by BBC Panorama and The Times into the 77-year-old businessman.
He has strongly denied all accusations and stood down as joint club chairman shortly before the investigation was broadcast in June, saying he wanted to focus on fighting what he called "factually incorrect and entirely false, decades-old allegations concerning my personal life."
London Stadium issued a statement on Tuesday saying safeguarding issues were behind their advice, but Sullivan has opted not to stay away.
London Stadium said: "Following media reports at the end of the season regarding a safeguarding matter being managed by the club, London Stadium sought further information to ensure it could fulfil its own safeguarding responsibilities.
"Based on the information provided by the club, we understand the matter was investigated and that the club does not consider there to be an ongoing safeguarding risk associated with Mr Sullivan attending the stadium.
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"However, given the potential for demonstrations and anti-social behaviour by some spectators, we have recommended to the club that he does not attend.
"We have also requested advanced notice of any planned attendance so that appropriate safety and operational measures can be put in place."
West Ham head coach Nuno Espírito Santo said: "We are focused on the pitch. The noise that comes from outside cannot distract us.
"We're going to find a lot of noise so we need to focus on the game, do our job, and the players did.
"It is good to start with a win, especially at home with 50,000 fans inside the stadium. We can't thank them enough, it's amazing."
There were no reports of any unrest among fans before or after the game kicked off against Portsmouth, whose 9,000-strong travelling fans helped swell the attendance to the largest ever for a Carabao Cup first-round match.
West Ham went on to beat Portsmouth 3-1 in an emphatic comeback victory to reach the second round, with Valentin Castellanos scoring twice.
Portsmouth took the lead in the 33rd minute when Adrian Segecic's effort deflected off Maximilian Kilman and into the bottom corner.
Castellanos equalised shortly before half-time from Mohamadou Kante's cut-back before captain Jarrod Bowen put West Ham ahead two minutes later with a deflected effort from range.
Castellanos added his second after the break, heading in Bowen's cross to seal the victory and give West Ham a winning start to the season two months after their relegation from the Premier League.