Christian charity CARE says the UK Government will fail in its duty of care, if it does not back a statutory levy on betting companies.
A debate will take place on Tuesday in Westminster Hall, where MPs will stress the need for a robust levy on betting companies, which the government has always said it supports.
But, last week, a government leak suggested that a long-awaited White Paper on gambling reform will not include the measure, urging the debate this week.
Ross Hendry, CEO of CARE, a social policy charity that leads campaigning for betting reform at Westminster, said: "Gambling related harm has a huge impact of people's lives, resulting in debt, depression, alcoholism, homelessness and even suicide.
"On average, one person commits suicide every single day as a result of gambling harm. Yet legislation remains out-of-date, and regulation remains lax.
"We call on MPs in all parties to hold the government's feet to the fire on gambling reforms. We need a new, evidence-led, public health approach that makes the industry truly accountable. Action is many years overdue."
"By retreating from sorely-needed reforms like a statutory levy on companies to fund research into addiction, Ministers will fail in their duty of care towards vulnerable gamblers, who have suffered significant harm.
"CARE and other organisations have long warned that gambling laws in the UK are simply not fit for purpose.
"Gambling addiction has grown exponentially in recent years. There are thought to be around 400,000 addicts in the UK, including 55,000 children.
A White Paper on reform is expected this month, after a series of delays. The shape of this paper will dictate how significant any changes to legislation are.