The number of problem gamblers in the UK has risen to more than 400,000, according to an update by industry regulator, the Gambling Commission, which warns that more needs to be done to tackle the problem.
The report, the first to cover the whole of the UK since 2010, found that 0.8% of the adult population can be classed as having a gambling problem.
Some 3.9% of the population is classed as “at-risk”, meaning more than 2 million people are either addicted to gambling or at risk of developing a problem.
The report comes just weeks before the government is due to release a delayed review into whether new restrictions should be placed on gambling adverts and controversial fixed-odds betting terminals (FOBTs).
Tim Miller, the Gambling Commission executive director, said: “We have a clear commitment to make gambling fairer and safer and these figures show that this is a significant challenge.
“Success will depend upon us, the industry, government and others, all working together with a shared purpose to protect consumers.
“The pace of change to date simply hasn’t been fast enough – more needs to be done to address problem gambling.”
The report found the types of gambling most likely to attract addicts are online gaming, poker played in pubs and clubs, and machines in bookmakers, such as FOBTs.
Just over half of online gamblers were classed as having a problem or at risk, while the figure for people using machines in bookmakers was 43.2%.
Campaigners have urged the government to crack down on controversial FOBTs, which allow punters to bet £100 every 20 seconds, and limit the spread of gambling adverts on television.
A spokesperson for the Campaign for Fairer Gambling said: “The increased rate of problematic gambling associated with FOBTs should alarm policymakers, particularly given that problem and at-risk gamblers make up only a fraction of those who experience harm.
“The bookies have claimed that because the overall population rate of problem gambling is static, FOBTs are not harmful. The data published today, which shows a rate increase, has totally undermined the bookies’ argument.”
Carolyn Harris, Labour MP for Swansea East, said: “This should be a wake-up call for government as we near the response to the FOBT review in October.
“43% of FOBT users are either problem or at-risk gamblers, so there can be absolutely no excuse – the government must recommend a reduction to £2 a spin to limit harm and addiction.”
British gamblers lost £13.8bn last year, including £1.8bn on FOBTs, which make up more than half of the annual revenue of bookmakers, most of whom oppose calls for the maximum stake to be reduced from £100 to £2.
The Association of British Bookmakers has previously dismissed any suggestions that FOBTs are linked to problem gambling.
But the machines have grown in popularity, with the amount lost on them up by 73% since 2009, despite the number of machines rising by just 9%.
There are now more than 34,000 of the machines in the UK, indicating that each one brings in an average of nearly £53,000 a year, about twice the national average wage.
Bookmakers are allowed a maximum of four per shop and some have been accused of “clustering” their outlets on the high street to fit as many machines in one area as possible.
While DCMS is understood to be minded to curb maximum stakes on FOBTs, Whitehall sources have told the Guardian that the Treasury opposes tough restrictions, fearing the impact on its tax take.
Earlier this month, the Treasury denied reports that the chancellor, Phillip Hammond, had ordered the review be scrapped.