Long-awaited government proposals to reform gambling laws are now unlikely to to be published until May, the Guardian understands, in a fresh delay that prompted a Labour MP to urge that turmoil within the Tory party must not disrupt the process.

The department for digital, culture, media and sport (DCMS) launched a review of gambling laws in December 2020, amid mounting concern over addiction and children’s exposure through advertising and football sponsorship.

A white paper was originally due to be published before the end of 2021 but was postponed until early 2022 after a cabinet reshuffle that saw John Whittingdale replaced as gambling minister by Chris Philp.

The proposals are now not expected until May, three sources with knowledge of the process told the Guardian, fuelling renewed concern among gambling addiction campaigners demanding urgent reform.

Carolyn Harris, who chairs a cross-party group of MPs examining gambling-related harm, voiced fears that the uncertainty surrounding the future of Boris Johnson, who is understood to be supportive of gambling reform, could disrupt the review.

“Of course time must be taken to gather the evidence to ensure the right reforms are put in place, but the gambling review was announced over two years ago,” the Labour MP said.

“Every day of delay leads to further gambling-related harm while the industry rakes in profits. The government must not let its own internal problems stand in the way of much needed reforms for this country – it is time for action.”

Liz Ritchie co-founded the charity Gambling With Lives with husband Charles after the suicide of their son Jack, who had become addicted to gambling while at school. “Someone takes their life every day in the UK because of gambling, so we simply cannot wait until May to see this white paper,” she said.

“How many more families need to be shattered by highly addictive gambling products and predatory gambling industry practices before the government acts?”

Ministers and officials at DCMS have been working closely with the industry regulator, the Gambling Commission, on potential reforms to improve protection for addicts and other vulnerable people.

But the regulator is under-resourced, according to reports by the Public Accounts Committee and the National Audit Office, while it is also overseeing the decision on which company will win the next 10-year licence to operate the National Lottery. A decision is expected this month or in early March.

Matt Zarb-Cousin, a former adviser to Jeremy Corbyn and recovering gambling addict who runs the campaign group Clean Up Gambling, said the review was urgently required “before more people are harmed as a result of regulation that is not fit for purpose”.

The government’s review of gambling laws has prompted a flurry of lobbying activity.

Campaigners for reform, helped by funding from the former casino and poker industry veteran Derek Webb, highlighted stories of addiction and transgressions by major industry operators.

The gambling industry’s links to MPs have come under scrutiny, including lucrative second jobs and hospitality lavished on politicians, some of whom were members of a group that wrote a controversial report criticising the Gambling Commission for trying to reduce gambling addiction.

The DCMS declined to comment.