Teams at Premier League and English Football League (EFL) games have been going down on one knee in support of the fight against racial injustice since June.

Millwall's Championship loss to Derby County and Colchester United's win over Grimsby Town in League Two on 6 December (AEDT) were overshadowed by some supporters booing the gesture.

Despite a strong backlash, the FA has ruled against formal disciplinary action against either club.

"The FA will continue to monitor and investigate should similar crowd-related incidents occur," a statement from the governing body read.

"The FA continues to support all players and clubs that wish to take a stand against any form of discrimination, and will always condemn the behaviours of anyone that chooses to actively oppose these values."

The Professional Footballers' Association revealed that players "overwhelmingly" supported continuing to take a knee and accused the EFL of showing "a lack of leadership" over the issue.

"This powerful symbol of solidarity represents the players' commitment to anti-racism and is not an endorsement of any political position," a PFA statement read.

"It is a peaceful act of unity that highlights a persistent and systemic issue."

Millwall Supporters' Club said its protest was targeted at the political views of the Black Lives Matter organisation, and was not motivated by racism.

Queens Park Rangers' director of football, Les Ferdinand, has previously spoken about how he feels the gesture has become "diluted" and is now "little more than good PR".

But the PFA feels the continued support for the gesture among players provides the mandate for competitions to give it its full backing.

"While the Premier League has already committed to teams taking the knee for the duration of the season, players across the EFL have been left in a difficult position following a lack of leadership on the issue," the PFA added.

A spokesperson for the EFL, which covers tiers two, three and four of the English game, said it respected "players' freedom of expression on this issue".

"By definition it has to be an individuals' choice as to whether they wish to take a knee before a match if it is to remain an effective stance," he added.