Kick It Out has condemned a number of incidents of abuse towards players, including Cyrus Christie and James McClean which marred the opening weekend of the English season.
Fulham's Christie alleged his sister was hit and racially abused during their match at Barnsley, while the anti-discrimination body also said McClean of Stoke, Southend's Theo Robinson and Barnsley's Bambo Diaby were subjected to abuse.
Kick It Out said: "We are appalled to hear that the sister of Fulham's Cyrus Christie was subjected to alleged violence and racist abuse on Saturday, with Southend's Theo Robinson, Stoke's James McClean and Barnsley's Bambo Diaby targeted with unacceptable discriminatory abuse too.
"On the first weekend of the season, these incidents should be a reminder for everyone in football that racism and discrimination cannot be ignored.
"Clubs and the football authorities must be relentless in calling out this disgraceful behaviour, and be prepared to issue strong sanctions and education sessions to any supporter involved.
"We have contacted the clubs to offer our support to the players, are liaising with the police and have informed the FA of all the incidents, so that whoever is responsible can be brought to justice.
"Discrimination casts a shadow over football in this country, and we will not stop highlighting the problem while it remains rife in the game."