Gambling firms will be banned from offering customers promotional bonuses on the condition they have to play more than one game, such as betting and playing slots.

Evidence shows that consumers are more at risk of harm when they gamble on multiple products rather than a single game, the Gambling Commission said.

Mixed promotions on different games can also confuse consumers because of complex terms and conditions, the watchdog warned.

It said the ban, which will come into effect on December 19, was aimed at reducing harm and boosting fairness and openness.

Operators will also be limited on the number of times customers must re-stake bonus funds to 10 before they can withdraw any winnings.

Some promotional offers include the condition that the consumer re-stakes any winnings multiple times before they are allowed to withdraw money from the bonus.

For example, a £10 bonus with a 50 times wagering requirement means the customer has to play through £500 before the winnings can be withdrawn.

The commission said such high wagering requirements could confuse consumers and lead them to gamble for longer, and faster, than they were used to.

Tim Miller, the commission’s executive director for research and policy, said: “These changes will better protect consumers from gambling harm and give consumers much better clarity on, and certainty of, offers before they decide to sign up.”