The competition regulator plans to take action against some online gambling companies which it thinks are breaking consumer law.
The Competition and Markets Authority (CMA) said some punters did not get the deal they expected from sign-up promotions that were offering cash bonuses to attract them to gaming websites. The CMA also said the firms were "unfairly holding onto people's money."
Nisha Arora, the CMA’s Director for Consumer Enforcement said: "New customers are being enticed by tempting promotions only to find the dice are loaded against them. And players can find a whole host of hurdles in their way when they want to withdraw their money."
The CMA launched its investigation into the gambling sector in October 2016. It has since heard from around 800 unhappy customers and as a result it has identified a number of operators engaging in practices that are likely to be breaking consumer law.
The controversial promotions involve terms and conditions which prevent gamblers from walking away with their winnings at the point of their choosing. For example, someone might bet £20 of their own money which is then matched by £20 from the online betting company.
However, in the terms and conditions of play it might state that the customer has to play several hundred times within a certain period of time before they can cash-in their winnings.
In some cases, under these 'wagering requirements' people have amassed winnings of several thousand pounds, but have had to keep on betting, increasing the chances of them losing their money. In other words, they don't have the choice to quit while they're ahead and walk away with their winnings.
The Remote Gambling Association (RGA) said "If there are generic lessons to be learned then, as ever, we will work with the Gambling Commission to bring those to the attention of the wider industry with a view to raising standards across the board."
Initially the CMA is talking to the companies involved, which it says it cannot name, demanding that they change their practices. If they do not meet the requirements, the CMA can take them to court. The court could fine the companies or revoke their licences.
The Gambling Commission has been working alongside the CMA on the investigation. It said identity checks were an "important duty" for the gambling industry to "prevent money laundering and to ensure responsible gambling".
But, it added, concerns had been raised that some operators might be "applying these requirements in a restrictive way, preventing consumers from legitimately withdrawing funds from their gambling accounts".
The online gambling sector has grown massively in recent years, increasing by about 150% since 2009. The sector is now worth £4.5 billion and the CMA estimate that more than 6.5 million people regularly use these online gambling sites.