Colin Kaepernick has hit out at the NFL, claiming the league are "blackballing" his former San Francisco 49ers team-mate Eric Reid, and accusing them of running "propaganda about how they care about Black Life".
Kaepernick and Reid participated in protests during the playing of the national anthem before NFL games to highlight social awareness and racial injustice in 2016.
The pair have both previously filed a grievance letter with the NFL, alleging team owners and the league colluded to prevent their employment due to the protest activities.
Quarterback Kaepernick has remained unsigned since 2017, while Reid joined the Carolina Panthers in 2018, but has been a free agent since being released in March this year.
Reid, a strong safety, had four sacks in 16 games for the Panthers last year and completed a career-high 91 tackles.
In a post on Twitter on Sunday, Kaepernick said: "While the NFL runs propaganda about how they care about Black Life, they are still actively blackballing Eric Reid for fighting for the Black community.
"Eric set two franchise records last year, and is one of the best defensive players in the league."
Sky Sports News has approached the NFL for comment.
Reid himself criticised the NFL on social media on Monday night after the league used video of Kaepernick kneeling on the sideline during its campaign for social justice.
NFL Week One games saw teams widely supported in making a stand, with some remaining on the field, some taking a knee, and others choosing to remain in the locker room.
'Lift Every Voice and Sing' - often referred to as the Black national anthem - was played before all of the games, while the playing of 'Star Spangled Banner' followed just before kick-off.
On Thursday, the Houston Texans remained off the field for both anthems, while the Chiefs remained on the field, and it was a similar story on Sunday as the players exercised their right to make a stand.
Just before kick-off on the same day, Miami Dolphins' strongly-worded video saw the players call on 'owners with influence' to flex their political power as well as their own reluctance to play their part in a 'publicity parade'.
As such, the Dolphins remained in the locker room before their game against New England, while in Washington the home team knelt for the anthem on the field and their opponents Philadelphia left the field.
Seattle and Atlanta both took a knee at Mercedes-Benz Stadium, while Jacksonville released a statement that was similar to many of the other teams that opted to stay off the field, saying they 'understood not everyone will agree with our position and demonstration... we hope that all will seek to understand the reason for it'.
Speaking on Sky Sports' NFL Sunday, Shaun Gayle said NFL players are understandably "sceptical" and called for "tangible action".
"You have to understand this systemic racism, this police brutality. It permeates society and life in the US and here," he said.
"When it comes down to addressing it, there is no room for a coat of paint, a publicity exercise. It has to be something valuable.
"Some tangible action to prove to those people being affected that something is going to take place."