POLICE are probing claims that Bolton Wanderers fans waged a sick hate campaign against the referee they believe cost the club a Premiership place last season.

Referee Barry Knight has reported receiving threatening letters -- aimed at him and his family -- since Bolton lost a crucial play-off clash with Ipswich.

Knight, of Orpington, Kent, controversially awarded three penalties against Wanderers in the stormy 5-3 defeat.

Wanderers manager Sam Allardyce was scathing about his performance saying: "He should never be allowed to referee again."

Knight has told police that since the game in May he has been bombarded with sinister letters, some of which include maps indicating where he lives.

Last night Mr Knight told the BEN that he did not wish to speak about the matter, but a spokeswoman for the Metropolitan Police confirmed that a complaint has been made and is being investigated.

She said: "I can confirm that we are investigating an allegation of malicious communication."

A Bolton Wanderers spokesman said the club would take a hard line with anyone found to be responsible.

He said: "Clearly it's alleged that Bolton Wanderers fans have been involved in a hate campaign against Barry Knight.

"If that is the case, we do not condone that type of behaviour and any Bolton fans proved to be involved face being banned from the Reebok Stadium.

"Bolton Wanderers would give full co-operation to any police investigation."

But Steve Abbott, editor of the Bolton Wanderers Supporters Association newsletter, questioned whether Whites fans were involved at all.

He said: "Referees don't just make one set of enemies. It could be someone pretending to be a Bolton fan, particularly someone who doesn't like us.

"Feelings have run high about Mr Knight. He literally cost us the chance to be in the Premiership which would have been ours but for his severe refereeing decisions.

"But I certainly disapprove of hate campaigns. I've done some part-time refereeing and it's bloody hard."

Wanderers fans enjoy a good reputation among many sets of opposition fans, with the club and supporters' groups both pointing to letters from other clubs praising the behaviour of the visiting Bolton contingent.

A so-called hooligans league table compiled last month put Bolton near the bottom, with only two fans subject to banning or restriction orders last season.

"There's no question we have got one of the best behaved crowds in Britain," the Wanderers spokesman added.

Knight, a father of three, first qualified as a referee in 1981 in the Woolwich and District League in London.

He first officiated in his first Premiership match, between Wimbledon and Middlesborough, last year.