MILLWALL have been left "shocked and appalled" by hidden-camera footage showing racist abuse at The Den this season, the club has said in a statement.
A three-month investigation by Sky Sports News culminated in the broadcast of a special report on Monday night that identified five individuals shouting abuse at home matches.
The club statement read: "Everyone at Millwall Football Club is deeply shocked and appalled by the footage shown on Sky Sports News on Monday evening.
"As a club Millwall has been at the forefront of the battle to eradicate racism from football, being the first in the country to introduce an Anti-Racism Trust.
"In spite of the incidents shown in this programme, tremendous strides have been made."
"However, it is a sad fact that a small minority of people in society still hold racist views and some individuals bring them into football stadiums throughout the country.
"We firmly believe that football itself is not the problem, but rather football is committed to being part of the solution.
"At Millwall we operate a zero tolerance policy in which we target, arrest and ban any fan identified displaying racist or abusive behaviour."
The programme featured footage filmed at the Lions' home match against Leeds in November, after which there had been reports that El Hadji Diouf had been racially abused.
The statement continued: "We became aware of allegations made initially via Twitter which were picked up elsewhere within minutes of the match ending.
"We immediately launched an investigation but there were no reports from officials, police, stewards or media at the ground to substantiate the allegations at the time.
"We spoke in person to the player in question and asked him if he was aware of being subjected to any racial abuse.
"He told us this had not been the case and, on that basis, we therefore had nothing to substantiate allegations of racial abuse and thus refuted them.
"Now that this new evidence has come to light, Millwall has requested that Sky make all footage available to the police, which they have agreed to do.
"We will assist in identifying the individuals concerned with a view to the strongest possible action being taken."