English football has been far too slow to tackle an environment where homophobia is still sometimes “tolerated” and gay players are scared to come out, a parliamentary committee was told on Tuesday. The warning came from the former NBA star John Amaechi, who said he was in contact with Premier League players who were afraid to be open about their sexuality because they knew their clubs and managers would not be supportive.

Amaechi, the first NBA player to come out in 2007, told MPs on the culture, media and sport select committee that there were “multiple” reasons why the gay Premier League players he knew had not come out, including fears of how they would be treated by their clubs. “Some of them feel that their team specifically would not be supportive,” he said. “Not their team-mates, but the coaches, the club and the administration around them. They either know them to be openly hostile, having stood in conversations or having overheard conversations that were incontrovertible, or suspected it. It is interesting how many of them I know are out to a greater or lesser extent to their family, friends and a selection of their team-mates. It’s amazing to me that people don’t realise that there are lots of players whose ‘manager’ picks them up after training – and that can’t always be the case.”

Amaechi also pointed to another reason why a top player had not come out: they did not want to be defined by their sexuality. “One day your achievements define you, the next day your sexuality does and I can tell you that is irritating.”

The British race walker Tom Bosworth, who came out as gay before the Rio Olympics, told the MPs that a gay footballer would be “a game-changer” for the way LGBT athletes were treated in the UK.

Bosworth said while British Athletics had been tremendously supportive to him personally, he was in contact with gay stars from other sports who had not come out, including one who was a “far bigger name than me” but was not in an “safe environment” to do so. “I think it highlights the support isn’t there from clubs, team-mates and managers all the way through,” he added.

Last year the Daily Mirror claimed that two Premier League players – including an England international – were preparing to publicly come out as gay by the start of the 2016-17 season and had the full support of their respective clubs and the Football Association. However, that did not happen, and it remains the case that no top British footballer has said they were gay while playing at the highest levels of the game.

In October the FA chairman, Greg Clarke, told MPs that he was “personally ashamed” no gay players in the Premier League had felt able to come out, and cited a small minority of people who hurled vile abuse at players as being the main factor.

But Amaechi told the select committee that while there was a small minority of fans who “became freed up to behave badly” when they entered football stadiums, the culture in the game “could be changed tomorrow” if senior figures in football had the will to act more firmly.

“In most businesses, managers get blamed for the people they lead. And yet somehow we are led to believe that fans are somehow feral and uncontrollable and we have got no choice to let them do what they want?” asked Amaechi, who said the lack of sanction for football’s leaders for sexist emails or homophobic behaviour in the past had sent a message to fans that what they did was OK too.

“Football has all the resources it wants,” he said. “It has the resources to hire the best cultural change people. We do not accept in workplaces the kind of things that we accept in sport. They could change it tomorrow if they want to. The fact they haven’t is down to their will. Nothing else.”

He also urged sporting authorities to provide education about homophobia for coaches at all levels after agreeing with one MP that he had never heard a Premier League manager talk about the issue. “They could demand coaches at every level stop being emotionally illiterate and intellectual disinterested troglodyte men who are willing to sustain the status quo as it stands,” he added.

Amaechi, who is black, admitted he was surprised to be still having a conversation about homophobia in sport. “This is not an intractable problem to be solved. The things that are tolerated with homophobia are not tolerated when it comes to race. It is a tacit message from sport that the colour of my skin is worthy of protection but my sexuality is not.”