Media playback is unsupported on your device Media caption Home Secretary Theresa May: "The victim is at the heart of what we're doing"

Life sentences will be brought in as part of a package of measures being proposed by Home Secretary Theresa May to tackle human trafficking.

The draft Modern Slavery Bill aims to increase the maximum custodial sentence for offenders from 14 years to life.

The draft bill would also create a new post of anti-slavery commissioner to hold law enforcement and other organisations to account.

The plans were first unveiled by Home Secretary Theresa May in August.

'Horrendous'

In an article for the Times newspaper, she said then that it was "scarcely believable" there was slavery in Britain, but the "harsh reality" was that there were people in the UK "forced to exist in appalling conditions, often against their will".

Slavery definition The Anti-Slavery Day Act 2010, which established an annual anti-slavery day to raise awareness of the issue, described slavery as including: Trafficking for sexual exploitation

Child trafficking

Trafficking for forced labour

Domestic servitude

The Modern Slavery Bill aims to consolidate the offences used to prosecute those who enslave others into a single act.

According to the Crown Prosecution Service, current legislation contains a range of criminal offences related to human trafficking including:

Trafficking in prostitution, under the Nationality, Immigration and Asylum Act 2002

Trafficking into, within, or out of the UK for sexual exploitation, under the Sexual Offences Act 2003, amended by the Protection of Freedoms Act 2012

Trafficking people for exploitation, under the Asylum and Immigration (Treatment of Claimants etc) Act 2004

Trafficking people for labour and other exploitation, under the Asylum and Immigration (Treatment of Claimants etc) Act 2004, amended by the Protection of Freedoms Act 2012

Conspiracy to traffic, under the Criminal Law Act 1977

In addition, the CPS advises, prosecutors in trafficking cases should consider whether "other offences such as rape, kidnapping, false imprisonment, threats to kill or causing or inciting prostitution for gain" are appropriate

There is also an offence of holding another person in slavery or servitude, or requiring them to perform forced or compulsory labour, under the Coroners and Justice Act 2009

The new bill would also provide for automatic life sentences for offenders with prior convictions for very serious sexual or violent offences.

One person who has experienced modern slavery, who gave his name as Mark, told BBC Newsnight he was offered work and a place to stay by a man who saw him leaving a soup kitchen.

Punishment beatings

Mark said he worked long hours, often getting up at 04:00 and labouring until as late as 23:00 with no breaks.

Media playback is unsupported on your device Media caption "There were people who had been here 10 years and they'd never seen a penny"

"I was paid nothing at all for the whole time I was working and that was standard," he said.

"There were people who had been here for a very, very long time - 10 or 15 years - and they had never seen a penny in that whole time."

He said workers were punished for behaviour like not working fast enough or dropping things - and punishments included beatings and even being hit with pickaxes and shovels.

Alongside the draft legislation, a review into modern slavery commissioned by the Home Office and carried out by Labour MP Frank Field will also be published.

Mr Field estimates that there are 10,000 victims of slavery in the UK.

But Mrs May told BBC Radio 4's Today programme: "The honest position is that we don't know whether that is the right figure, or whether there are fewer or indeed more victims in the UK.

"What we do know is that we have seen more referrals to what is called the national referral mechanism, where people are able to refer people who they think have been trafficked, who they think are the victims of modern slavery, into a central mechanism.

"The number of referrals has been increasing, and it's on that basis that we believe that we have seen an increase in this absolutely horrendous and appalling crime."

The founder of human trafficking charity Hope for Justice, Ben Cooley, welcomed the proposals.

"We've learnt from experience that victim welfare is inextricably linked to the prosecution of perpetrators," he said.

"This bill is a critical step towards ending slavery in our country but going forwards we must all ensure that victims are supported so they don't disappear on the other side of initial after-care provision just to be re-trafficked."

Shadow home secretary Yvette Cooper said there was cross-party support for the Bill but it should include legal protection for child victims. She said two thirds of children rescued from trafficking in Britain went missing again after being found by the original gang.

"You would have a legal guardian for those children, so someone is responsible for them, see the whole of their case, make sure the care they got was expert, that it was far away from their abuser, understand that they are still at risk and still need protection," she told BBC Radio 4's Today programme.

England and Wales

Media playback is unsupported on your device Media caption Labour's Yvette Cooper: ''We want the government to go further''

Chloe Setter from the children's rights charity ECPAT UK also said she feared the focus of the bill was too narrow.

"There appears to be very little in regards to victim protection for adults or children which is something that we believe is crucial and should be at the heart of any bill trying to tackle slavery and trafficking."

The bill will also include Trafficking Prevention Orders to restrict the activity and movement of convicted traffickers and stop them from committing further offences.

The bill - which the Home Office says will be the first of its kind in Europe - will only apply specifically to England and Wales but ministers said they wanted it to have the "broadest UK-wide effect".

A consultation will be held in Northern Ireland on the way forward while the UK and Scottish governments have agreed to work together while ensuring Scotland's "distinctive approach" to the issue is maintained.