West Ham joint-chairmen David Gold and David Sullivan have urged the club's fans to show impeccable behaviour in the clash against Chelsea after they were heard viciously abusing Tottenham fans last week.
Tottenham's 3-1 victory over their London rivals at White Hart Lane last weekend saw a section of Irons travelling supporters mocking the stabbing of a Spurs fan in Rome. While they were also heard hissing - mimicking the sound of Jews being gassed during the Second World War - and chanting the name of Adolf Hitler.
Now, Gold and Sullivan have written an open letter to the club's fans, urging them to "show the world what being a West Ham fan is all about''
Their open letter, published on the club's official website, read: "Saturday's match with Chelsea promises to be thrilling affair and we know we can count on all of you to provide the customary passionate backing for the team that we have witnessed in every game since we arrived at the club.
"That is why we were disappointed to read about the actions of the small section of fans that let the club down during last Sunday's game at Tottenham Hotspur. We were not only disappointed because they reflected badly on our club, but they misrepresented the tens of thousands of outstanding supporters who follow the team home and away throughout the season.
"We have both been sent hundreds of emails and have personally spoken to a number of fans, who have all told us that they share our sentiments and are angry that the reputation of their club has been besmirched by the actions of a few mindless individuals.
"We have said to them what we will say to you now - it is up to us all to not tolerate anything that we deem to be unacceptable when supporting West Ham United. In the rare case that you do see or hear anything inappropriate, there are a number of ways you can report the matter.
"Two of the easiest ways are to speak to your nearest steward at the stadium or use the Boleyn Ground's anonymous fan phone number - 07860 404 069 - where all calls will be treated in the strictest of confidence.
"We have made it very clear over the past week that we will not tolerate any form of discriminatory behaviour and one by one we will root out those fans that do not deserve to represent this great club of ours.
"Everyone at West Ham United is looking forward to Saturday's visit of the champions of Europe, Chelsea, and given the news reports of this week, it is inevitable that much focus will be on our club this weekend. This fixture will hopefully provide us with the perfect opportunity to show the world what being a West Ham fan is all about - supporting with pride, passion and respect.''
The east London club have already taken swift action, with one of their fans banned for life because of the chanting and two supporters cautioned by police for a racially aggravated public order offence.
The Hammers' tough stance has been praised and Lord Herman Ouseley, Chair of Kick it Out, said: "Kick It Out is encouraged by the swift action taken by West Ham United in the wake of Sunday's fixture.
"Clubs have the power to show leadership and set an example for the vast majority of its supporters to follow in instances like this. Here, they've done exactly that.
"Kick It Out has seen first-hand the appetite the club has in embracing anti-discrimination initiatives, with David Gold and James Tomkins both acting as campaign ambassadors in 2012. By doing this they're helping to send a message as to what is and what isn't acceptable.
"It is clear they feel abuse of this kind won't be tolerated and, in a period where the issue is high on the agenda, this approach is something we applaud.''
Information from the Press Association was used in this report