Millwall say they are "appalled" by the footage to have arisen on Monday night which appears to show their supporters aiming racial abuse at Leeds forward El-Hadji Diouf.
Sky Sports News aired clips which appeared to show Senegal international Diouf being abused during a game between the two clubs at the Den on November 18.
"Like all Millwall fans and football fans generally, we're appalled by the footage we've seen," said Lions chief executive Andy Ambler.
"Clearly that behaviour is unacceptable in any football ground in the country and at Millwall we will ban the individuals for life and we hope that Sky will pass the footage to the police so that further action can be taken.
"Sadly racism exists in our society and certain individuals want to bring it into football grounds. It's down to us in football do to more. We think football is the solution to the problem and the work that we do will continue and we need to continue it. That day against Leeds obviously there was an allegation of abuse made online initially. We investigated it straight away.
"We interviewed stewards, police, players, we looked at the TV footage too as it was live on Sky. After speaking to the player who had the alleged abuse at him during the day, he said that he heard no abuse on the day so that was basically at that point the end of the investigation - although we're going to open it again now."
Bolton forward Marvin Sordell has previously made allegations of racial abuse towards Millwall's fans. In the wake of him doing so, a banner claiming "Sordell is a c***" was unfurled at a later game, while a 13-year-old boy was banned from the ground.
Sordell, who represented Great Britain at the London 2012 Olympics, has faced racial abuse on social media websites and claims he is not shocked that such things still occur.
He said: "We're a developed, multi-cultural society. It's surprising it can still go on - but it doesn't exactly shock me. We can't be silent about it. We need to make people aware that there is a problem going on and only when people are aware of the problem can it be sorted out.
"As long as people are brave enough I'd say to come out and say exactly what's happened to them then I think we'll be going in the right direction because the first thing that needs to happen is that we can't be silent about it.''