Ministers must take "immediate action" to end the growth of people trafficking in the UK, MPs and peers say.
Trafficked women have been found throughout the UK
Unpublished Home Office figures suggest 4,000 women victims of trafficking for prostitution were in the country at any one time in 2003, an inquiry found.
The Joint Committee on Human Rights is calling for more protection for immigrants and specialist support for victims of sexual exploitation.
The Home Office would "look carefully" at the proposals, a spokeswoman said.
'Serious human rights issue'
The committee described trafficking as "one of the most serious human rights issues in the modern world".
Official figures say between 142 and 1,420 women were trafficked to the UK in 1998.
Of even greater concern is the lack of knowledge we have of the extent of the trafficking of young children
Andrew Dismore, committee chairman
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The committee said that: "10 years ago, 85% of women in brothels were UK citizens [and] now 85% were from outside UK".
It also called for data on men and children trafficked for work to be compiled.
The government had to set up a national identification system and improve training in the identification of victims.
The committee's chairman, Labour MP Andrew Dismore, said: "The growth and extent of people trafficking into the UK is extremely worrying.
"We should recognise women trafficked for prostitution through deception, fear and violence as victims of this serious crime and not immigration offenders or criminals themselves.
"Of even greater concern is the lack of knowledge we have of the extent of the trafficking of young children, for domestic servitude or, even worse, labour in the drugs trade."
'No adequate system'
Workers were often "trapped by violent and abusive employers", he added.
Daniela Reale, exploited children adviser at Save the Children, said: "At the moment there are no adequate systems in place for these children.
"Any child who has been trafficked will have had a deeply traumatic experience and will need crucial specialist support including safe house accommodation, access to education and basic services and support to address the trauma they have experienced."
Children's charity NSPCC also said more help was needed for children.
"Child trafficking is a cruel and abhorrent form of child abuse," NSPCC head of policy and public affairs Natalie Cronin said.
"The children involved are particularly susceptible as they may not speak English, and have no one to turn to for help."
The UK is a major destination for human trafficking victims, mostly women forced to work as prostitutes, the United Nations says.
The committee's report urges the government to publish research into organised crime markets. The research is currently being conducted by the Home Office.
The protection of victims should be the focus of all policies, it adds.
And the government should sign and ratify the Council of Europe Convention on Action Against Trafficking in Human Beings, the report says.
A Home Office spokeswoman said: "The Home Office co-operated fully with the JCHR inquiry and provided both written and oral evidence.
"We will now look carefully at the report and its recommendations."