Keir Starmer has been urged to follow through on the previous government’s plan for a £100m-a-year levy on gambling companies.

In an open letter to the prime minister, “deeply concerned” advocates of the proposal issued a warning that a delay could cost lives.

The Conservatives published a white paper on reform of gambling regulation last year but many of its proposals have been left up in the air by Labour’s election victory.

One significant measure yet to be finalised is a statutory levy on gambling companies’ revenues to fund research into problem gambling, education and treatment.

The levy was expected to raise £100m, which would be spread between the NHS, which would oversee treatment; UK Research and Innovation, for research into gambling harms; and the Office for Health Improvement and Disparities, looking at harm prevention. However, the plan was not included in policy proposals laid out in the king’s speech last week.

Campaigners for gambling reform have also expressed misgivings about ties between senior Labour politicians and the betting industry and what impact the relationships might have on the future of plans set out in the white paper.

In their open letter to Starmer, members of the House of Lords, campaigners and academic researchers called on the government to publish its response to a public consultation on the levy and implement legislation to enact it.

“For years, the gambling industry exerted influence over the research, prevention and treatment of gambling-related harm by providing inadequate funding through a voluntary system,” they said.

Writing that they were “deeply concerned by the delay to enact a statutory levy”, the letter’s signatories called on the government to press on with it.

“This commitment has received support from all sides of the political debate, as well as leading NHS clinicians and academic experts,” they said.

They said any delay “will lead to further harm to mental health, damage communities across the country and, ultimately, will cost lives”.

Signatories include the chief executive of the Samaritans, eight members of the House of Lords, academics and campaign groups.

Gambling-related harm is expected to come into sharper focus this week when the Gambling Commission publishes figures based on a new set of methods. These figures are expected to indicate that rates of problem gambling may be higher than previously thought.

When the regulator issued an experimental survey using the new methods in November last year, it showed that 2.5% of the population may be suffering from problem gambling;the previous estimate was 0.3%.

The commission is also expected to publish evidence of the links between gambling and suicide.

Supporters of the levy say the current system of voluntary donations gives the industry too much influence over funding intended to help the very people that bookies and online casinos make their money from.

A government spokesperson said: “As stated in the government’s manifesto, we are absolutely committed to reducing gambling-related harm.

“We will ensure responsible gambling and strengthen protections for those at risk.”

Some measures included in the white paper are already set to go ahead, including a cap of between £2 and £5 on digital slot machine stakes, while a pilot scheme testing the effectiveness of affordability checks to stop punters losing vast sums is under way.

Other proposals have been left in limbo by the change of government, including proposals for a gambling ombudsman to settle disputes between customers and operators.

The white paper avoided action to curb gambling advertising, although Premier League teams will voluntarily forgo betting sponsors on the front of shirts from the season after next.