Everton Football Club has condemned the behaviour of fans who disrupted a tribute to victims of the 1989 Hillsborough disaster.
Club officials said the club was badly let down by supporters who shouted abuse during a minute's silence before Sunday's Merseyside derby at Goodison Park.
Fans of both teams were asked to pay silent respect to the Liverpool fans who died at Hillsborough, and to the victims of last week's South African stadium tragedy.
But according to reports sections of the crowd in the ground's Park End stand started to shout abuse less than 15 seconds into the silence.
Witnesses say the referee was forced to cut the silence short as the situation worsened.
The match was played just a day after the 12th anniversary of the FA Cup semi-final when 96 fans lost their lives following a crush on the Leppings Lane terrace of Sheffield Wednesday's Hillsborough ground.
The behaviour of a minority of Everton fans contrasted sharply with supporters attending Liverpool's home game against Leeds on Good Friday when the minute's silence was impeccably observed.
Everton FC's spokesman Ian Ross said: "As a club we condemn wholeheartedly the actions of these people. What happened during the minute's silence was obviously unforgivable. On the other hand I would have to stress, it was a very, very small minority.
"For people to condemn Everton in general for the actions of a few would be wrong."
Mr Ross said the 40,000-plus crowd made it difficult to isolate those responsible for disrupting the tribute.
"If right-thinking Everton fans know who these people are then contact the club and we will look into it further," he added.
Trevor Hicks, chairman of the Hillsborough Family Support Group, said he was "bitterly disappointed" by the outburst.