Unsigned quarterback Colin Kaepernick is making plans to potentially pursue a claim of collusion by NFL teams, accusing them of improperly conspiring to keep him out of the league, according to a person familiar with the deliberations.

Kaepernick opted out of his contract with the San Francisco 49ers following last season. The team has said it would have released Kaepernick rather than retaining him under the terms of that deal. He has remained out of work, being passed over by teams in favour of other quarterbacks following a 2016 season in which Kaepernick refused to stand for the national anthem prior to games, as a protest of the treatment of African-Americans in the US.

Former San Francisco 49ers quarterback Colin Kaepernick (centre) kneels during the US national anthem. Credit:AP

The NFL is expected to decide this week whether to force players to stand for the national anthem.

NFL Commissioner Roger Goodell said last year that he supported players who want to see change in society, even if he didn't necessarily agree with the protest.