The maximum stake for fixed-odds betting terminals (FOBT) should be cut to £30 or less, the Gambling Commission has recommended.
High-stake, high-speed electronic casino games are said to be dangerously addictive and currently allow a stake of up to £100 every 20 seconds, enabling a player to theoretically gamble away £18,000 an hour.
The Gambling Commission has said the stake limit for FOBT non-slot games, including roulette, should be set at £30 or less.
It suggested the limit for FOBT slots stakes should be £2.
The watchdog said the measures are necessary "if it is to have a significant effect on the potential for players to lose large amounts of money in a short space of time".
The advice, to support the Government with a review of gambling machines, was among a raft of suggestions designed to help minimise the risk to vulnerable people.
Gambling Commission chief executive Neil McArthur said: "We've put consumers at the heart of our advice - advice which is based on the best available evidence and is focused on reducing the risk of gambling-related harm.
"In our judgment, a stake cut for fixed-odds betting yerminals alone doesn't go far enough to protect vulnerable people.
"That is why we have recommended a stake cut plus a comprehensive package of other measures to protect consumers.
"We have proposed actions that will tackle both the risk of harm and provide solutions that are sustainable in the longer term."