Measures to protect victims of people smuggling are "not fit for purpose" and may be illegal, a report claimed today.
Campaigners accused the British Government of breaching its obligations under European law to protect trafficked people and uphold minimum standards of care.
They said border officials focus on the immigration status of victims and not on crimes such as sexual exploitation and forced labour.
And they warned shortcomings in the national operation mean vital intelligence about criminal gangs is being lost to police.
Kate Allen, of Amnesty International, said an overhaul of the system must change the emphasis to protecting victims not "hounding people" for immigration crimes.
She said: "We pushed hard for the government to sign up to the anti-trafficking convention but the government has botched its attempt to deal with this most despicable of crimes.
"In particular, the identification system is clearly not fit for purpose, with under-trained staff displaying ignorance over what trafficking actually is."
Researchers at the Anti-Trafficking Monitoring Group examined measures launched 14 months ago, including changes to identify trafficking victims more quickly.
In a report titled "Wrong kind of victim?", they said the process is "flawed" and may discriminate between people from different parts of the world.
Campaigners said there is evidence criminals control people by warning they will be seen as illegal immigrants, not victims.
Border staff were singled out for failing victims of sexual exploitation and forced labour, including children.
The report highlighted how only 36 trafficking-related cases were prosecuted in the nine months to January 2010, while 5,000 victims of smuggling are in Britain.
It called for the appointment of an anti-trafficking watchdog and the introduction of an independent appeals system.
Aidan McQuade, of Anti-Slavery International, said viewing trafficking as a form of immigration crime has led to "arbitrary decisions".
He said: "Evidence gathered in this study shows that this is undermining the ability of the police to combat the trafficking gangs who are making fortunes from the misery of others."
Christine Beddoe, of ECPAT UK, said: "Children are not 'mini-adults' and attempting to fit them into a system designed for adults is inappropriate. The experiences and needs of children are quite different to those of adult victims.
"It is essential that children are provided with a legal guardian to ensure that their best interests are always considered."
ECPAT stands for: End Child Prostitution, Child Pornography and the Trafficking of Children for Sexual Purposes.
The Anti-Trafficking Monitoring Group is a coalition of campaign groups including Anti-Slavery International, Amnesty International and ECPAT UK.