The owners of William Hill, Ladbrokes Coral, Paddy Power Betfair, Skybet and Bet 365 will increase their voluntary levy on gambling profits from 0.1% to 1% up to 2023 - a contribution of £60m.

It will be "a step change" in how they tackle addiction, the firms claimed.

It comes amid criticism of the industry on how little it spends to help addicts compared with its marketing budget.

Earlier this month, NHS England chief executive Simon Stevens warned betting firms could be taxed to pay for addiction treatment.

Mr Stevens condemned the "fraction" spent by industry on helping those struggling with addiction, compared with the amount spent on advertising and marketing.

The companies said cumulatively they would spend £100m on treatment over the next four years.

Last month, when the BBC broke the news of the plans, a source said the industry had to act: "The industry is on a precipice - if we don't get ahead of this, we will end up where the alcohol industry was 10 years ago, and tobacco 30 years ago.

"The fear is that we face a ban on touchline advertising or football shirt sponsorship."

Peter Jackson, chief executive of Flutter Entertainment - the holding company name for Paddy Power Betfair - said the agreement marked "an unprecedented level of commitment and collaboration by the leading companies in the British betting and gaming sector to address gambling-related harm".

He told the BBC's Today programme: "We think that is an important step to make.

"We do think we need to increase the amount of money that is available to protect the young and vulnerable."

'Tone and content'

Marc Etches, chief executive of charity GambleAware, told the BBC: "We welcome this initiative by the leading operators as it's essential there is sufficient funding to provide for treatment and support for both problem gamblers and for those who are 'at risk' - particularly the young and vulnerable.

"Customers should be able to gamble in a safe environment, where help and advice is readily available at the point of need.

"It is vital that we work closely with the commission, government and other organisations to ensure that operators continue to focus on making gambling products safer, and that treatment and support is properly funded alongside other initiatives including the Safer Gambling campaign, Bet Regret."

The five firms have also agreed to increase safer gambling messages in their adverts and review the "tone and content" of their marketing and sponsorship material.

The Gambling Commission estimates there are 430,000 people with a serious gambling addiction in the UK. If you include those they deem at risk of addiction, the number rises to more than two million.

Of these, around 55,000 are children and young people aged 11 to 16.

Jeremy Wright, Secretary of State for Digital, Culture, Media and Sport, said the gambling industry had a responsibility to tackle problem gambling and contribute to the cost of treatment to rebuild the lives of those affected.

"We will monitor closely the progress of these new measures and encourage the wider industry to step up. The government will not hesitate to take further action to protect people from gambling related harm."