Former Collingwood player Seamus McNamara has hit out at the club and several past and present players for their silence on Heritier Lumumba's claims he was subject to racial vilification during his time with the Magpies.

McNamara has come to defend Lumumba and slam coach Nathan Buckley, former president Eddie McGuire, captain Scott Pendlebury, former captain Nick Maxwell and former teammate Luke Ball in a damning Twitter thread on Thursday.

The former Magpies forward also revealed McGuire requested that McNamara remove a social media statement in regards to the then-Magpies president's comments on Sydney star Adam Goodes in 2013.

McNamara revealed he was one of seven past members of the club to "acknowledge that racism did exist within the club", stating his disappointment in the sparse support for Lumumba by his former teammates.

"Although I have spoken & stood by Heritier Lumumba, regarding how he was treated during and after Collingwood, I have bitten my tongue for far too long and I can no longer stay silent in what has really bothered me," McNamara wrote on Twitter.

"In โ€˜13, I made a social media statement on Ed's comments about Adam Goodes. I then got a text from Ed saying โ€œSide by Side?โ€ And asking me to take it down. I told him that I'd take it down - choosing to support him cuz we all make mistakes, but he knew I was disappointed.

"Truly standing โ€œSide by Side" with someone, is acknowledging & holding one accountable to BE better. I've never outed anyone & always chose to have the focus be on the bigger picture.

"Before I break down my disappointment through acknowledging and holding people accountable to be better, I will do it under these categories: The Fans, The past members of the club, the current leaders of the club.

"For the ones angry with Heritier โ€“ a few things: 1.The interpersonal racism happened (i.e. racist jokes, nicknames, stereotypes etc.) 2. He's not bitter because he was traded โ€“ he was traded because he wouldn't stop addressing the toxicity in the club.

McNamara continued to express his disappointment in key members of the club, stating their silence "has exacerbated the pain of Heritier & those affected by this the community".

"The fact that there has been total silence from all of the players who know it went on is disappointing. Until you acknowledge this truth, you are not free from your regret," McNamara continued to write.

"There are a few people I need to acknowledge, for not doing the right thing in speaking up back then and now. You need to know how much your silence on the issue has exacerbated the pain of Heritier & those affected by this the community."

McNamara named Ball, Maxwell, Buckley, McGuire and Pendlebury in his criticism of the club's stance.

"Luke Ball (X AFLPA President), I know you were very close with Heritier in and outside of the club. You knew what he went through and you chose to stay silent when you could have validated his experience. Your self-preservation is really disappointing, McNamara wrote.

"Nick Maxwell, You were his brother, for real. He lived with you and you named your dog after him because it's black. Your silence in choosing your self-preservation with the club is really disappointing.

"Coach Buckley, You tried to publicly deny this for several years... Why are you hiding now? Are you still being all that you can be?

"Eddie McGuire, You've made yourself and the club what it is โ€“ a massive success. With that, takes great pressure and responsibilities. It's unfortunate that you fumbled a lot of chances to get it right and take the right path.

"Scott Pendlebury, This is your moment to lead, brother. The last time I saw you, I gave you two leadership books. After your 400+ games, you will be the next CFC coach. In my eyes, your culture starts now โ€“ Let's go!"