Roberts was sent off early in Millwall’s FA Cup fifth-round defeat at Selhurst Park on Saturday for a high challenge which left Mateta needing 25 stitches around his left ear.

The FA said the standard three-game ban is “clearly insufficient” and has submitted a claim to a regulatory commission to increase it.

BBC Sport has been told that Millwall will contest the claim.

The club said in a statement that they will “continue to support” Roberts after the “horrendous online abuse” he has received.

At half-time during the game Palace chairman Steve Parish described the challenge as “the most reckless I’ve ever seen”.

On Monday Millwall said reporting of the incident “contributed to an unwarranted character assassination” of Roberts.

Millwall said he contacted Mateta after the match “with an apology which was accepted immediately”.

Roberts, who served the first game of his ban as Millwall lost 2-0 to Bristol City in the Championship on Tuesday, has until Thursday to respond to the FA.