Victims of modern slavery are left without the help they need, because of the high threshold for accessing Government support, a campaigner has said.

Marissa Begonia, coordinator of campaign group Voice of Domestic Workers, said many victims were also scared to come forward because of the threat of deportation.

Reports of modern slavery are increasing nationally, with 30 per cent of victims from London – almost three times more than any other region.

Crimes include human trafficking and domestic servitude, as well as debt bondage, descent-based slavery and forced marriage.

In 2015 the Government expanded its National Referral Mechanism (NRM) – previously for human trafficking only – to include all forms of modern slavery.

It is designed to connect victims with the help they need, but Ms Begonia believes many vulnerable people are excluded from the system.

Speaking at the London Assembly’s police and crime committee on Thursday, she said: “The way the NRM system works, they need to be raped, to be beaten, to be starved to death to access protection.

“I think there’s a big difference, and we should properly differentiate: workers are workers, victims are victims.”

Tamara Barnett, head of office at the Human Trafficking Foundation, said modern slavery remained under-reported, partly because of stereotypes about the crimes involved.

She said: “Our mindset about what a victim is has dramatically changed compared to several decades ago, let alone a decade ago.

“I think we’re beginning to finally recognise vulnerability.”

Ms Barnett said that while modern slavery is often associated with foreign nationals, British victims are the largest group referred to the NRM.

British referrals to the Government programme almost doubled last year compared to 2017, up from 820 to 1,625.

And last week, the Mayor outlined the scale of child exploitation in London through the County Lines drug trade – a form of coerced labour that sees children from the capital selling drugs in other parts of the country.

More than 4,000 children in the city are involved, working in 41 counties.

Detective Superintendent Phil Brewer, head of the Metropolitan Police specialist crime and vulnerabilities unit, said it was about “where you set the bar in terms of what you consider to be modern slavery”.

He said: “We always talk about modern slavery – we’ve talked about it for years – but in terms of exploitation its a very small part of what we see.

“If you asked me to put a figure I’d say there are thousands of people in London who are exploited.”