British police launched an investigation on Monday after two England internationals were subject to abuse on social networking site Twitter.
Ashley Young and Ashley Cole were targeted after missing penalties in England's Euro 2012 quarter-final loss to Italy on Sunday.
A Metropolitan Police spokesman said: "We are aware of alleged racist comments on Twitter following last night's England game and have launched an investigation.
"The allegation was made to MPS on 25 June by a member of the public relating to comments on a Twitter account supposedly based in London.
"No arrests at this early stage.
The Football Association branded the Twitter attacks as "appalling and unacceptable".
"We are concerned at the reports regarding allegations of abuse aimed at England players Ashley Cole and Ashley Young on Twitter," an FA statement read.
"They have just given everything for the national team at Euro 2012 and it is appalling and unacceptable that messages of an abusive type are being posted. We support any police investigation in identifying who is behind this."
Cole and Young, who returned home with the remainder of the England team on Monday, were singled out for abuse by one user following the 4-2 shoot-out defeat.
In a series of offensive postings, the user goaded others who criticised him for his rants.
In one post the tweeter wrote: "All I got to say is this was just a joke, you guys need to relax, police know i was kiddin around and they won't bother me hopefully, cheers."
Another said: "The police won't bother me mate i can assure you that."
In March, student Liam Stacey was jailed for 56 days after racially abusing two Twitter users and mocking Bolton midfielder Fabrice Muamba after he collapsed and almost died.
The 21-year-old British student was released in May after serving half his sentence.