Angry fans were trying last night to sabotage the auction of mementoes handed out as a goodwill gesture by Manchester United for Sunday’s tribute to those killed in the Munich air crash. United executives came up with the generous idea of placing a commemorative scarf on each seat before the derby match at Old Trafford against Manchester City, with 73,000 in red and white for United supporters and another 3,000 in blue and white for Manchester City fans.

Supporters from both sides of the city turned Old Trafford into a sea of colour as they raised their scarves during the tribute before the match. Fears that the memorial would be disrupted by City fans proved unfounded and the minute’s silence was observed “impeccably”, according to Ken Ramsden, the Manchester United club secretary.

Unknown to United officials, unrest was already stirring in the packed stands. Some fans claim that their scarves were stolen before they got to their seats, which meant that they missed out on what will be a treasured memento for many. Their disappointment turned to anger as word spread that adverts for the memorial scarves had started to appear on eBay, the auction website, within hours of the final whistle.

Supporters’ groups were up in arms, calling on fans to boycott the auctions. Albert Scanlon, a survivor of the Munich disaster, said: “You don’t go to these things to make money.” Sandy Busby, the son of Sir Matt Busby, United’s former manager, added: “Sunday’s game was an emotional event that the club and the fans handled magnificently. It is just sad that people are trying to cash in on mementoes of a special day and the tragedy it marked. Unfortunately, I don’t think you can stop this kind of thing.”

Some United fans decided that they could stop it by taking matters into their own hands, placing false bids for some of the merchandise. One item spiralled from a first bid of £10 to what was clearly a tongue-in-cheek offer of £9,999,999. One seller, from Glossop in Derbyshire, stood to make about £5,000 from a genuine bid but posted a plea alongside the entry for his scarf, on sale with the covering letter from David Gill, the Manchester United chief executive, that went out to all fans on Sunday. “For the people who obviously don’t agree to me selling this,” he wrote, “I paid for my seat at Old Trafford, I was given the scarf and it is mine to do so as I wish. I am sorry if you don’t agree, but it is my choice.”

However, there were clear signs that the intervention by United supporters had had an effect and more than 70 items for sale on eBay had been reduced to a handful last night as some sellers decided to pull out rather than risk the ire of fellow supporters.

Although trivial by comparison with the scale of the Munich disaster, the row over the eBay scarves served to test myths and loyalties. The fears before Sunday surrounded City supporters and whether they would disrupt the pre-match Munich tribute and the minute’s silence. Ramsden acknowledged their contribution. “Manchester came together and that was wonderful,” he said. “There was some trepidation obviously, because the families were here. It only takes one or two people out of 76,000, so it could have easily gone wrong. But I think the fact that it didn’t is a great tribute to both clubs, and particularly Manchester City.”

Ironically, there was a single memorial scarf in the blue and white of Manchester City on sale on eBay among the plethora of United scarves listed, while claims by some supporters’ groups that the scarves were put on sale only by football tourists with no emotional ties to United were somewhat undermined by the fact that most of the offers were listed by fans living in Manchester and the North West — proof, perhaps, that some so-called real supporters may know the price of United merchandise but not its true value.