Chelsea on Thursday night questioned the "brain-power" of some of their supporters after a group of fans were heard singing an anti-Semitic chant in Budapest – just five days on from the alleged racism directed at Raheem Sterling.

Only two minutes into their Europa League group match away at MOL Vidi on Thursday, a minority of the 1,273 Chelsea supporters at the match began chanting abuse about "Yids".

Singing a chant that has become wearingly familiar to Chelsea regulars, the words "Barcelona, Real Madrid, Tottenham are a bunch of Yids... Yiddos" could be heard from the Groupama Arena away end.

After the match ended in a 2-2 draw, Chelsea released a statement condemning the behaviour of the supporters in question. "Anti-semitism and any other kind of race-related or religious hatred is abhorrent to this club and the overwhelming majority of our fans,” a club spokesperson said. "It has no place at Chelsea or in any of our communities.

"We have stated this loud and clear on many occasions from the owner, the board, coaches and players. Any individuals that can’t summon the brain-power to comprehend this simple message and are found to have shamed the club by used using anti-Semitism or racist words or actions will face the strongest possible action from the club.”

Raheem Sterling was allegedly racially abused by Chelsea fans at the weekend credit: Getty Images

Uefa later said they will wait to read the referee's report before deciding what action to take. Chelsea manager Maurizio Sarri was asked about the controversy after the match but said: "I didn’t hear anything. I am not able to understand a song in English, I am sorry."

A spokesperson from Kick It Out, added: "We've been made aware of the alleged chants and will liaise with the club."

The controversy was exactly what Chelsea were hoping to avoid in a week that has seen them ban four supporters for allegedly racially abusing Sterling. One of the fans is accused of calling Sterling a "black c***" – though he claims he used the word "Manc". Chelsea are investigating the incident and the Metropolitan Police are carrying out their own inquiry, though the club may decide to uphold the bans even if the police decide to take no action.

In Budapest, the anti-Semitic abuse was followed by a chant attacking a freelance journalist and Chelsea fan who earlier in the week called out the racism and discriminatory behaviour he claimed to regularly see at Stamford Bridge. An eye-witness in the Chelsea end also claimed that she heard a supporter call one of the players a "poof".

Chelsea have made major steps to try and eradicate discriminatory behaviour among their fanbase, but they have had to deal with a number of scandals over the last few years. In 2015, four supporters were given suspended prison sentences and ordered to pay €10,000 to a black commuter pushed off a Metro carriage in Paris. Fans on that occasion chanted: "We’re racist, we’re racist, and that’s the way we like it."

In the wake of the incident, Chelsea tightened up how tickets could be accessed for away matches in an attempt to sideline the extreme elements of their fanbase. But in spite of these measures, Chelsea supporters have still reported hearing racist and discriminatory chants, including hissing noises made to mock holocaust gas chamber victims and other anti-Semitic songs.

It has been an issue that has plagued Chelsea for decades, and was brought to a mainstream audience by ex-undercover reporter Donal Macintyre's expose of racist Chelsea hooligans in a BBC documentary almost 20 years ago.

Earlier on Thursday meanwhile, Manchester City midfielder Ilkay Gundogan praised Sterling for calling out the abuse he suffered at Stamford Bridge last Saturday. “It is something we all have to fight,” said Gundogan. “We all have to play our individual roles to make it better for everyone.

"Raheem has had a lot of support this week [after what happened against Chelsea]. He has been normal to be honest. I think he made his point clear through Instagram, giving a statement on that.

“I don’t know if there is any more to say about that, but this is obviously something that doesn’t belong anywhere in the world, but it happens."

Gundogan, who was booed and jeered while playing for Germany because of his Turkish heritage, continued: "We have to deal with it. It’s not easy because I lived it in the summer as well. I know how that feels and it hurts.

"But, at the end of the day, we have no other choice but to stay strong and try to go through that period and try to do our best on the football pitch. To keep being successful, that’s what matters."

Anti-racism campaigner Piara Powar added that he believes "difficult political times" since the Brexit referendum have contributed to the recent alleged racist incidents.

As well as Thursday night's incident and the Sterling abuse, a Tottenham supporter threw a banana skin at Arsenal striker Pierre-Emerick Aubameyang during the north London derby earlier this month. The supporter later claimed his actions were not racially motivated.