Bookmakers could be forced to pay a levy to fund NHS treatment under new plans to curb problem gambling, deputy Labour leader Tom Watson will announce.

Labour will launch a probe into how mental health services are coping with soaring numbers of addicts after a recent report found the number of over-16s deemed problem gamblers had grown by a third in three years.

Mr Watson, the Shadow Culture secretary, will rail against gambling firms that are “deliberately targeting” the most vulnerable and outline a review into a tax to fund NHS treatment for those whose lives are “blighted by addiction”.

The Gambling Commission has estimated that around 430,000 people over 16 suffer from a serious habit, while more than two million people are either problem gamblers or at risk of addiction.

Speaking at the Labour party conference, Mr Watson will say: “Some gambling companies, driven by greed, are deliberately targeting our poorest communities even as hundreds of thousands of lives are ruined by addiction. The number of problem gamblers in this country has risen by a third in just three years. Two million people are either problem gamblers or at risk of addiction.”

Children and young people are being targeted by betting adverts, while some betting firms make it difficult for addicts to opt out of online gambling, he will claim.

Mr Watson was due to add: “Gambling companies are even harvesting data to deliberately target low-income gamblers and people who have given up gambling. More than half of companies profit from ‘risk’ gamblers. This has to stop. Gambling companies must be held to account for this abuse of trust and power.

“Can you imagine the uproar that would ensue if drinks manufacturers targeted members of Alcoholics Anonymous by selling vodka outside AA meetings? We wouldn’t tolerate that – and we should no longer tolerate the same pattern of irresponsible behaviour by some bookmakers.”

The party has also pledged to crack down fixed-odds betting terminals by reducing the maximum stake from £100 to just £2 and demanded a ban on bookmakers sponsoring football teams.

Gambling firms voluntarily contribute 0.1 per cent of their gross gaming yield – the amount taken in bets minus winnings – to GambleAware, which funds education, prevention and treatment services.

The Association of British Bookmakers, which represents high-street betting shops, said it backed an “evidence-based approach to helping problem gambling in the UK” and would support the probe, if it facilitated this. A spokesman said: “We also would not oppose an appropriate, compulsory levy on the gambling industry to fund problem gambling treatment, as we have long argued that the gambling industry needs to work together to reduce the number of problem gamblers and address the fact that most problem gamblers move between different forms of gambling.”