Football chiefs in England have written to the bosses of Twitter and Facebook calling for action to tackle "havens of abuse" after a spate of online racist incidents.
An open letter to the platforms' chief executives Jack Dorsey and Mark Zuckerberg asks them "for reasons of basic human decency" to address the stubborn problem.
A number of players including Manchester United trio Anthony Martial, Marcus Rashford and Axel Tuanzebe, as well as Chelsea full-back Reece James, have been targeted on social media in recent weeks.
"The language used is debasing, often threatening and illegal," said a letter published Thursday.
"It causes distress to the recipients and the vast majority of people who abhor racism, sexism and discrimination of any kind.
"We have had many meetings with your executives over the years but the reality is your platforms remain havens for abuse."
Signatories include Football Association chief executive Mark Bullingham, Premier League CEO Richard Masters and referees' chief Mike Riley.
"Your inaction has created the belief in the minds of the anonymous perpetrators that they are beyond reach," they said.
The letter calls on the platforms to put in place mechanisms to filter or block posts with racist or discriminatory content, take down offending material and ensure an improved verification process to identify account holders.
Instagram, owned by Facebook, announced new measures to tackle online abuse on Wednesday, saying it would remove accounts being used to send abusive messages.
The letter from football chiefs acknowledged the steps being taken but said "far more is needed to drive change".
A Facebook spokesman said the company removed "hate and racism" when it found it.
"The new measures we announced yesterday, which include tougher action when we become aware of people breaking our rules in DMs (direct messages), further build on the work we do to tackle this," he added.
Twitter released a statement saying there was "no room for racist abuse".
"We will continue to take swift action on the minority that try to undermine the conversation for the majority," it said.
Earlier Thursday, Newcastle manager Steve Bruce revealed that people had wished him dead on social media, while Premier League referee Mike Dean has received online death threats.
"We've got to police it better and there are some vulnerable people out there," said Bruce. "When I see the nature of some of it, it's totally and utterly vile. Some of the stuff I've had has been obscene.
"You feel the hatred and something has to be done."
Culture Secretary Oliver Dowden said on Wednesday tech giants could face hefty fines under new legislation proposed by the British government.
"We're introducing a new age of accountability for these (social media) companies through our upcoming Online Safety Bill and this could see huge fines for firms which fail to clearly and transparently protect their users," he said.