Ministers will come under intense pressure from a cross-party group of MPs this week to follow the US by banning so-called prostitution websites amid mounting evidence that they are enabling a huge growth in sexual exploitation and the trafficking of women to the UK for profit.

Members of the all-party group on prostitution have secured a parliamentary debate during which they will demand that the Home Office acts to make websites such as Vivastreet and Adultwork accountable under law for encouraging and profiting from sexual exploitation.

The websites make money by placing advertisements on behalf of gangs and individuals running networks of women, many of whom are trafficked from abroad. Vivastreet operates in 19 countries and is owned by an offshore holding company based in Jersey. Adultwork is registered in Panama.

A recent inquiry by the all-party group heard evidence from the Joint Slavery and Trafficking Analysis Centre – a multi-agency intelligence unit set up by the police, the government and the National Crime Agency – which concluded that “adult services websites represent the most significant enabler of sexual exploitation in the UK”.

This was because the sites are at the heart of a money-spinning online industry that allows networks of women to connect with men who want to buy sex. Investigators believe much of the profit made by those managing the women is then used to fund a wider network under which vulnerable women are sought out abroad and systematically trafficked to the UK.

Amid rising outrage about the use of such websites, US President Donald Trump signed a bill earlier this year that gives federal and state prosecutors greater power to act against platforms that make money out of such advertisements. The bill also enables victims and state attorneys general to file lawsuits against the sites.

The MPs say it is now crucial that the Home Office follows the US by changing the law in the UK to make such websites directly accountable under law for encouraging exploitation and trafficking. They will demand swift action from Theresa May, who made action to stamp out modern slavery a top priority during her time at the Home Office and reiterated the same commitment on entering Downing Street.

Sarah Champion, MP for Rotherham and a member of the all-party group, said she would attend the debate and press whichever Home Office minister represents the government to follow America’s swift action. “UK legislation needs to be radically overhauled to keep pace with the changing face of prostitution,” Champion said. “We need to update our laws to make websites legally accountable for facilitating and profiting from sexual exploitation. The idea that commercial prostitution sites make it safer for women is not true.”

Diane Martin, who was awarded a CBE for services to vulnerable women and survived trafficking and prostitution in her late teens, now supports exploited women. “As a survivor, my perspective means firsthand experience of the realities of prostitution,” she said. “My years of supporting hundreds women to exit prostitution have also only strengthened my fervent belief that we are failing some of the most vulnerable women in society unless we address the demand of the buyers and the greed of the pimps.

“Currently, UK legislation is inadequate to deal with this. I want to call on MPs, and all those with the power to make positive change, to see the reality of prostitution, to be on the side of the most vulnerable and to adopt an approach under which pimps, brothel owners and third-party exploiters are not tolerated.”

A spokesman for Vivastreet said: “Vivastreet is a classified advertising platform that allows users to post adverts for goods and services across a broad range of categories. We take the issue of exploitation extremely seriously, and we are working closely with the Home Office to help develop an industry-wide approach to identifying and preventing online trafficking. We would urge all sites to engage with this process.

“We are committed to eradicating any potential exploitation from our platform, and we have a wide range of measures in place to detect and remove inappropriate material. We report any suspicious content to the police via our long-term partnership with National Ugly Mugs, a specialist charity that works with police forces across the country and is formally supported by the National Police Chiefs Council.”