Four in five modern slavery victims are being denied justice after cruel new Tory laws came into force, experts have warned.
Campaigners said the Nationality and Borders Act, which came into effect in February, has allowed traffickers to "act with impunity".
Former Prime Minister Theresa May is among those sounding the alarm over the impact of the new law on vulnerable victims in the Commons last week.
Greater Manchester's Operation Challenger, which battles organised crime, said just 18% of victims received positive first decisions when they reported abuse in February and March.
This compared to 95% before the legislation came into force.
This means investigations are dropped and suspects do not face prosecutions - and charities fear the pattern is being replicated across the country.
Justine Carter, director of charity Unseen, told The Mirror that the impact of the Act had been "significant" for potential victims.
Ms Carter said: "We have been clear for some time about the impacts that such an approach would have, including fewer victims coming forward to support prosecutions.
"This legislation simply allows the perpetrators to act with impunity because it prevents vulnerable individuals of all nationalities from seeking help to extract themselves from exploitative situations.”
Jamie Fookes, UK and Europe Advocacy Manager at Anti-Slavery International, told The Mirror that victims have been left vulnerable to "dangerous exploitation".
He said: "Support workers now need to provide an unreasonable amount of evidence, essentially blocking many victims from support.
"The Act also blocks many people who have been criminally exploited, such as through county lines (many of whom are young people), from accessing the vital support needed to take them out of exploitation and keep them safe.."
He added: "We are devastated to see our concerns coming true. This Government continues to neglect victims of trafficking, rolling back their support and increasing the risk of trafficking."
Mr Fookes said: "Rather than providing a source of hope for victims, the Nationality and Borders Act is making it harder for people to access support."
In an update published last week, police-led Operation Challenger said the bill had "an immediate impact on potential victims".
"This has seen positive first stage decisions drop from around 95% of all submissions to 18% of submissions between February 20th and March 31st.
"This means that 4 in 5 potential victims are not able to access immediate support from the national modern slavery and human trafficking victim care providers."
Mrs May challenged Immigration Minister Robert Jenrick on the figures in the Commons last week.
She said: "If he is not worried, is it because he feels that the 2022 Act is already having an impact? In which case, why does he need modern slavery provisions in this Bill?"
Mr Jenrick responded: "She and I have a disagreement on the current impact of modern slavery on our system, but to me the evidence is very clear that unfortunately - this was never the intention of the framework that was created - there is significant abuse.
"We see that in particular in the number of individuals who are coming forward with modern slavery claims in the detained estate when we seek to remove them from the country. Such last-minute claims currently account for 70% of individuals."
A Home Office spokesman said: “Each year we support thousands of victims of modern slavery - a barbaric crime which we are fully committed to eradicate.
“It has become clear that some elements of our system needed reform to allow the UK to appropriately use its resources and to ensure decision makers are best able to identify victims so that support as well as assistance is targeted to those who need it.
"We have now fully reviewed the guidance used by decision makers assessing modern slavery claims. Updated guidance will help ensure they focus decisions on objective factors and evidence of someone being a victim."
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