In what appears to be a response to the incident at the Millwall-Derby game, the English Football Association said it "supports all players and staff that wish to take a stand against discrimination in a respectful manner, which includes taking of the knee."
It "strongly condemns the behaviours of any spectators that actively voice their opposition to such activities," the FA said.
The topic of players taking a knee was discussed on a Millwall fans' forum this week and a statement from the first-team squad was published on the club's official website on Friday.
"As a squad we are fully supportive of the entire football family's efforts in ridding the sport, and society generally, of all forms of discrimination," the statement read.
"It is our duty as players to reinforce the positive messaging and action of clubs, community trusts, charities and governing bodies, and we do so with great pride and knowledge that so much good work is being done up and down the country. The gesture of 'taking the knee' before matches provides an opportunity for us to do exactly that and continues to allow all those playing to publicly showcase their support — on behalf of the whole squad — for the fight against discrimination."
It added that the gesture of taking a knee is, in the club's view, "in no way representative of any agreement with political messaging or ideology."
"It is purely about tackling discrimination, as has been the case throughout," the statement read.
Millwall, a club from east London, was renowned for its struggle with hooliganism in the 1970s and '80s.