England and Manchester City forward Raheem Sterling has accused some sections of the media of helping to “fuel racism” with their portrayal of young black footballers after he was the victim of alleged racist abuse during City’s 2-0 defeat at Chelsea.

The Metropolitan Police and Chelsea are investigating an incident during the first half of Saturday’s game at Stamford Bridge when Sterling retrieved a ball from beyond the touchline in front of the Matthew Harding stand. Footage was posted on social media of home supporters leaning forward screaming obscenities and one fan allegedly subjecting him to racist abuse.

Five stewards approached the fan in question just before the final whistle and, having allowed him to watch the last few minutes of stoppage time, appeared to accompany him away from his seat at the end of the game. The police have since confirmed no arrest was made.

The incident came after a troubling week for football which saw a Tottenham Hotspur supporter arrested for throwing a banana skin at Pierre-Emerick Aubameyang during Arsenal’s derby victory at the Emirates stadium. Two people were also arrested in Edinburgh on Saturday for allegedly directing racial abuse at Motherwell’s Christian Mbulu during his side’s defeat at Hearts, with the anti-discrimination body, Kick it Out, calling for leaders in football to take a more proactive approach in dealing with racism in the sport.

Sterling took to Instagram on Sunday morning to suggest he was not surprised by the behaviour of the supporters in question. “I just want to say, I am not normally the person to talk a lot but when I think I need my point heard I will speak up,” he posted. “Regarding what was said at the Chelsea game, as you can see by my reaction I just had to laugh because I don’t expect no better.”

The England international screen-grabbed a story that had appeared on MailOnline last January about his club-mate, Tosin Adarabioyo, under the headline: ‘Young Manchester City footballer, 20, on £25,000 a week splashes out on mansion on market for £2.25m despite having never started a Premier League match’. He went on to reference another story from October about City’s teenage midfielder, Phil Foden, buying a house which had carried the headline: ‘Foden buys new £2m home for his mum’.

“You have two young players starting out their careers – both play for the same team, both have done the right thing, which is buy a new house for their mothers who have put in a lot of time and love into helping them get where they are,” wrote Sterling. “But look at how the newspapers get their message across for the young black player and then for the young white player. I think this is unacceptable, both innocent, have not done a thing wrong but just by the way it has been worded.

“The young black kid is looked at in a bad light. Which helps fuel racism an[d] aggressive behaviour. So for all the newspapers that don’t understand why people are racist in this day and age all I have to say is have a second thought about fair publicity an[d] give all players an equal chance.”

Lord Ouseley, the founder of Kick it Out, said: “We have already made comments about the way Raheem Sterling has been treated differently by the media. Raheem Sterling has received bad press over the last few years because of his lifestyle and clearly there are issues from potential stories adding to prejudice, and I have every sympathy for him.

“What happened at Chelsea shows what is still going on in football. Where is [Premier League chief executive] Richard Scudamore? Where is [the Football Association chairman] Greg Clarke? Where is Chelsea’s chairman [Bruce Buck]? They should have been talking out last night and it has to dealt with at the top. We do not have any leadership at the top of the game to speak out. They rely on Kick it Out.”

It is unclear whether Sterling had made out the specific nature of the abuse as he retrieved the ball. “Players know if they are abused in any way they have to tell the referee,” added Lord Ouseley. “It was awful. All players know the referee is in charge and has a duty of care, and the referee can remove those people. It didn’t appear to me he told the referee in the first place.”

Chelsea have pledged take the strongest possible action where necessary and have requested video and audio from BT, who were broadcasting the game. Their own CCTV footage will also be handed over to the police. They will also speak with stewards to ascertain what was said to the man after the final whistle as he was led away. They are under orders to eject offenders and bring in the police for any racist behaviour.

It is unclear as yet whether the man alleged to have shouted the racist abuse is a season ticket holder or member, or whether he had simply bought a match ticket for the fixture. If identified and found guilty, he will be banned for life though, if he denies the accusations, the club reserve the right to impose a similar sanction on the balance of probability, as they have on occasions in the past.

“We take all allegations of discrimination extremely seriously and will work with the clubs and the relevant authorities to ensure this matter is dealt with appropriately,” said the FA in a statement. “We strongly condemn all forms of discrimination and encourage all fans and participants who believe that they have been the subject of, or witness to, discriminatory abuse to report it through the appropriate channels: the FA, our County FAs or our partners Kick It Out.”

Police Scotland have been given footage which shows around 20 fans in the main stand at Tynecastle shouting comments at the Mbulu, 22, as the substitute warmed up on the touchline. The Motherwell manager, Stephen Robinson, described the abuse as “dark ages and dinosaur stuff”. Hearts have confirmed they are cooperating fully with the police in their enquiries, with anyone found to have abused Mbulu to receive indefinite bans.