About 50 Vietnamese former child slaves were denied asylum in Britain after they turned 18 last year.
Statistics from the British government indicate only 54 candidates were rejected refuge in the three years from 2014 to 2016, according to Thomson Reuters Foundation.
Lawyers say a number of young illegals are forced to leave the country after being jailed for offenses committed whilst being enslaved.
Debbie Beadle, the program director of ECPAT UK — an anti-slavery charity, said young victims smuggled from Vietnam are being depicted as criminals instead of victims.
Scotland has seen a rise in such cases. Suspected cases of human trafficking have jumped from 150 in 2016 up to 213 cases in 2017. Half of the potential victims were from Vietnam.
Scottish Justice Minister Humza Yousaf said trafficking and exploitation were an abuse of human rights, and that the government emphasizes the needs of victims. So far, the Scottish government has spent more than 3 million pounds (US$3.9 million) for support services that will last till 2021.
But experts said despite clear support from British authorities, many Vietnamese slaves stay hidden in the shadows in fear of deportation or even repercussions from traffickers on families back in their homeland.
According to figures from the Global Slavery Index formulated by the Walk Free Foundation, there are at least 136,000 modern slaves in Britain, which is ten times the official estimate given by the government in 2013.