The Football Association announced on Monday that it is investigating following the booing of players taking a knee at two English Football League games at the weekend.

A number of fans at the match in the second-tier Championship between Millwall and Derby and at Colchester's League Two home clash with Grimsby booed the players' anti-racism gesture before kick-off.

"The FA can confirm that investigations are under way into crowd-related incidents at both The Den and JobServe Community Stadium on Saturday 5 December 2020," English football's governing body said in a statement.

The booing from Millwall fans led interim Derby boss Wayne Rooney to condemn their "disgraceful and mindless behaviour".

And Colchester owner Robbie Cowling, whose side play in the fourth tier, has told supporters who want to boo players taking a knee they are not welcome at the club.

A flag flies above The Den stadium in south London
A flag flies above The Den stadium in south London AFP / Ian KINGTON

"Those taking the knee, and supporting the taking of the knee, not only show their willingness to support the drive to eradicate racial oppression but force it to be a talking point even when it's uncomfortable," he said.

The Professional Footballers' Association described the booing as "a sad indictment of the lack of understanding and empathy for the players' fight against racism and discrimination".

It urged London-based Millwall to "act swiftly to identify the section of the crowd who booed the players".

Players from Millwall and Queens Park Rangers will stand arm-in-arm with each other in a show of solidarity for football's fight against discrimination ahead of kick-off at The Den on Tuesday

The two teams will hold a banner to show their collective commitment towards ongoing efforts to rid the game of racism.

"Millwall believe that this gesture, which the club hopes to repeat with other visiting teams in the coming weeks and months, will help to unify people throughout society in the battle to root out all forms of discrimination," the club said in a statement.