Britain’s National Crime Agency on Tuesday reported a sharp 22-percent rise in suspected human trafficking cases in 2013 from the previous year, including hundreds of children.

The report found 2,744 potential victims in Britain last year, and cited reports that some traffickers were even branding their victims with tattoos and “various symbols signifying ownership or to show that a victim is over 18”.

“Modern slavery is an appalling crime that has no place in today’s society,” Modern Slavery and Organised Crime Minister Karen Bradley said in a statement.

“These figures show it is taking place here — often out of sight — in shops, fields, building sites and behind the curtains of houses on ordinary streets,” she said.

The report found that 602 of the cases reported involved children — a 10-percent increase from 2012 — with British, Slovakian and Vietnamese children the most frequent victims.

Some 65 percent of the children were girls who were being sexually exploited, while boys were more likely to be trafficked for other criminal activity and illegal labour.

The highest number of reported trafficking victims were from Romania, followed by Poles, British people and Albanians.

Other than prostitution, there were reported cases of slavery in roadworks, car cleaning, fishing and domestic service.

The agency said the rise in numbers may reflect better identification by the police and more willingness to come forward but it stressed the problem was also under-reported.