At least two United players claim they heard the insult as members of Sir Alex Ferguson's squad clashed with Chelsea groundstaff and officials during their warm-down on Saturday.
Last night Chelsea sources disputed the claim that Bethell called United defender Evra a 'f*****g immigrant', suggesting instead that he said 'f*****g idiot'. It is understood Bethell has already denied the allegation of racism.
United's decision to defend their players is bound to increase tension between the two clubs as their battle for the title reaches a dramatic finale.