The gambling industry is braced for new limits of as little as £2 a spin for online slot machines, the Guardian understands, in a move that could cost casino companies hundreds of millions of pounds.

The government has been consulting on imposing a maximum stake for the digital casino-style games since publishing a white paper on gambling reform last year.

The Guardian understands that the new limit, which will be announced on Friday, will be £2 for under-25s, similar to the limit imposed by the government on fixed-odds betting terminals (FOBTs) in 2019.

There will be a higher limit of £5 a spin for anyone over that age.

At the moment, there is in effect no limit on the amount that gamblers can stake on the games, which carry a higher rate of addiction than other products, such as betting on football. Some of the larger operators do impose limits voluntarily.

An industry source said: “We’re expecting it to be £2 and £5. We’d be very surprised if it wasn’t.”

The restriction could cost the UK gambling industry hundreds of millions of pounds in revenues but is likely to be welcomed by campaigners concerned about the danger of addiction.

Online casinos are the largest and fastest-growing segment of the gambling industry, accounting for £4bn of the sector’s £11bn in revenues last year, excluding the national lottery.

Of that £4bn, slots account for £3.2bn, according to the latest statistics from the Gambling Commission, for the year to March 2023.

The Department for Culture, Media and Sport declined to comment. It is expected to announce details of its plans for online stake limits on Friday.