The prevalence of betting advertising among Premier League clubs is "dispiriting", a Christian charity has said.
CARE analysed shirt sponsors for the 2021-22 season and found that 9 out of 20 teams have a betting ad on their strip - the same proportion as in 2018.
Overall, 19 clubs have some form of partnership with a betting firm, meaning that adverts can appear on their websites or stadium noticeboards.
Leicester City was found to have the most gambling sponsors, at four this season, followed by Spurs with three.
Norwich City was the only Premier League team without any ties to a betting firm after its partnership with BK8 ended in June.
CARE said the rate of gambling sponsorship among Premier League clubs suggests they are not taking the problem of related harms seriously.
"The continued prevalence of gambling-related advertising in the Premier League is dispiriting," said CARE's James Mildred.
"There is growing concern about the level of problem gambling in the UK, fuelled by an industry that bombards sports viewers relentlessly with offers, without due warning of the risks.
"Football clubs are fully aware of this problem, yet many seem to be doing little to curb those responsible."
The Championship league fared slightly better with only six teams out of 24 displaying betting sponsors on their shirts, well below the 17 in 2018.
However, 15 Championship teams still have some form of relationship with a betting firm, CARE said.
"The fact that close to half of top tier clubs have gambling ads emblazoned across the chests of players is especially hard to stomach. There has been no change to the extent of this advertising in 4 years," Mr Mildred continued.
"The presence of ads on shirts sends a message that gambling is harmless fun. For many thousands of families blighted by addiction, this couldn't be further from the truth.
"Premier League bosses should follow the lead of their contemporaries in the Championship who have broadly moved away from including betting companies as main club sponsors. It's time bosses truly stepped up for vulnerable fans by showing betting companies the red card."
The warning comes after a study by GamCare earlier this year revealed a 9% increase in calls to the National Gambling Helpline during the pandemic.
A report from the House of Lords last year estimated the number of problem gamblers in the UK at 340,000, including 55,000 aged 11 to 16.
Mr Mildred added, "It is time we had a serious public debate about the gambling industry's relationship with football. We have an epidemic of problem gambling in the UK.
"We have to question whether the Premier League and other footballing authorities are doing enough to protect vulnerable fans."
