Several former footballers have spoken out about being abused.
Several former footballers have spoken out about being abused after ex-Crewe Alexandra player Andy Woodward came forward to reveal he was abused by convicted child molester Barry Bennell in the 1980s.
A pre-existing inquiry into child sex abuse in Britain said it was "watching events closely", while England captain Wayne Rooney has urged anyone who may have been assaulted to seek help.
The Metropolitan Police, Britain's largest force, said it had "received information relating to non-recent sexual abuse in football clubs in London".
Hampshire Police, Cheshire Police and Northumbria Police, from southern, northwest and northeast England respectively, said they were all investigating non-recent child sex abuse claims.
Northumbria Police said it was looking into an allegation by an unnamed former Newcastle United player that he was abused in the club's youth system.
Newcastle said they would co-operate with authorities "if or when the club receives further information".
The Premier League said it was "very concerned" by the allegations.
Former Manchester City youth team player Jason Dunford told the BBC he felt there was a "conspiracy and paedophile ring" within football circles in the northwest of England in the 1980s.
Former England and Manchester City players David White and Paul Stewart and ex-Crewe player Steve Walters have also spoken out about being sexually abused by football coaches as children.
Bennell, who worked for Crewe, Manchester City and Stoke City, sexually abused young boys across three decades from the 1970s onwards.
He was given a four-year sentence for raping a British boy during a football tour of Florida in 1994 and a nine-year sentence for 23 offences against six boys in England in 1998.
He was jailed again in 2015 for abusing a boy at a football camp in Macclesfield, northwest England, in 1980.
Crewe's director of football and former manager Dario Gradi said the club, currently playing in England's fourth tier, would carry out an internal investigation into Bennell's links with the club.
Gradi, Crewe's manager from 1983 to 2007, has claimed he knew nothing of Bennell's crimes until his conviction in the United States in 1994.
But a former Crewe director, Hamilton Smith, says the club held talks about an allegation of sexual abuse against Bennell in the late 1980s, but decided to keep him on.
"I'm incredibly angry the club continue to refute that they knew anything about suspicions of Bennell's activities," Smith told The Guardian.
"This was discussed at the club's top level and, as much as I tried to resolve this, regrettably I couldn't. I dread to think how many victims there are, and my heart goes out to them."
Premier League heavyweights Manchester City are also reviewing Bennell's connections with the club.
Operation Hydrant, an investigation into allegations of institutional child sex abuse, has asked police forces in England and Wales to pass on details of the allegations they have received in recent days.