LONDON- Chelsea promised Monday to take action if it was proved that any of their supporters had made threats against referee Anders Frisk which convinced the Swedish official to retire.
"We would like to make it absolutely clear that both the club as a whole, and our manager and first-team coach Jose Mourinho, condemn any threats made to Mr Frisk, his family or friends which may have, in any way, influenced his decision to retire as a referee," Chelsea said in a statement.
"If there is any evidence of such behaviour by Chelsea fans then we would totally disassociate ourselves from them and we would welcome any such evidence to be passed to us so we can investigate and take the appropriate action."
Last weekend Frisk, 42, quit, saying: "The game is just not worth all that. The safety of my family is more important than anything.
"I received threats by telephone, e-mail and the post. I have a big family and I am very worried. Anything could happen."
Frisk, one of the top-rated referees in the world, had given Didier Drogba a second yellow card in the 56th minute, causing the Chelsea striker to be sent-off, while the Londoners were 1-0 up.
Frisk decided Drogba had raised his foot too high in a challenge on Barcelona keeper Victor Valdes early in the second-half though Drogba later claimed he had not touched the player.
Drogba's dismissal aroused the anger of Chelsea fans and of manager Jose Mourinho who claimed Barcelona coach Frank Rijkaard had entered Frisk's changing room during the break.
"I have so much experience that everyone should understand that I would never let a coach enter my changing room during a match," Frisk insisted on Saturday.
Earlier Monday, Mourinho was branded an enemy of football for critcising Frisk, in a match Barcelona won 2-1.
Mourinho also incurred the wrath of UEFA for saying he expected Italian referee Pierluigi Collina to be handed the second leg against Barcelona, which his team won to progress to the quarter-finals.
Collina was given that game, but Mourinho was reprimanded for calling for the appointment.
Chelsea went on to win 4-2 to qualify for the quarter-finals 5-4 on aggregate.
Volker Roth, chairman of UEFA's Referees' Committee, said Mourinho and other coaches were responsible for making fans turn on match officials.
"It's the coaches who whip up the masses and actually make them threaten people with death," Roth said.
"We can't accept that one of our best referees has been forced to quit because of this.
"People like Mourinho are the enemy of football," he also told The Times.
Last September Frisk had also been in the middle of an incident during a Champions League match between AS Roma and Dynamo Kiev.
Frisk abandoned the match with the Ukrainian club leading 1-0 after being hit by a coin thrown from the stands during the half-time break at the Olympic stadium in Rome.
Roma were later handed a 3-0 defeat by European football's governing body UEFA and ordered to play two home matches behind closed doors.
Frisk refereed 132 international matches and appeared at three European championship finals (1996, 2000, 2004) and one World Cup finals (2002).
03/14/2005 20:15 GMT