A quarter of trafficked children who were in the care of local authorities in the UK last year have gone missing from the system, according to new research by two British charities that work with vulnerable children.

The new figures raise serious questions about the capacity of local authorities to provide a safe environment for vulnerable children who arrive in the UK alone, or after being rescued from trafficking gangs. The report – to be published this week and seen by the Observer – shows that of the 1,015 children reported by local authorities as identified or suspected victims of trafficking in 2017, 24% – 246 – have gone missing from the care system.

The charities ECPAT (Every Child Protected Against Trafficking) and Missing People found that, in total, 5,780 unaccompanied and trafficked children were reported as being in local authority care in 2017, an 8% increase on 2014-15. The study found 15% of unaccompanied children had also gone missing from care. Overall, 190 of the total missing children have not yet been found. The findings are from Freedom of Information requests to 217 local authorities with responsibility for children’s social care in England, Wales, Northern Ireland and Scotland.

Jane Hunter, co-author of a Missing People report, said: “Trafficked children are going missing at a rate of more than 30 times that of other children, and more than double that of other looked-after children.” This is happening despite government attempts to improve the system of identifying trafficked children through the national referral mechanism (NRM). There were 2,118 children referred to the NRM in 2017, a rise of 66% on the previous year, but the true number of trafficked children is likely to be much higher, based on UK government estimates.

“Trafficked and unaccompanied children are particularly vulnerable, and may go missing back into a highly exploitative situation to those they were trafficked by or others,” said Hunter.

Catherine Baker, co-author of a report from ECPAT, said it was “an on-going hidden scandal that so many child-trafficking victims and unaccompanied children continue to be failed by the UK care system”.

The data is based on research conducted by the charities in partnership with University College London. It shows that in comparison with a previous report published in 2016, the numbers of trafficked children had increased by 58% up from 590 from 2014-15. Baker said these figures might show “some tentative signs of improved identification and recording”. Though she cautioned that “whilst there are signs that identification of these children may be improving, it appears as though safeguarding responses may be getting worse”. The data identified that for some local authorities, missing trafficked or unaccompanied children made up a significant proportion of their overall looked-after children population.

In Kent, missing trafficked and unaccompanied children made up 15% of all children in the care of the council’s children’s services. Of the missing children Hunter said, “almost 20% have still not been found and remain in harm’s way”.

Across the UK 38 local authorities reported having at least one child who had not been found, with Kent having the highest number at 38, followed by Rochdale at 17 and central Bedfordshire at 14.

British children make up the second largest group, after Vietnamese, in the study’s numbers. Hunter said. “These figures [show] that trafficking is not something that only affects those trafficked into the UK, but also those trafficked within the UK. Specialist support should be made available for these children, who may be being groomed and criminally exploited, including through ‘county lines’.”

Despite the increase in the numbers of missing trafficked and unaccompanied children, Baker said, “funding for children’s services has been drastically reduced”. She added that “it is unacceptable that there is still no systematic collection of this data and that it is not centrally recorded, leaving harm done to these children largely invisible”.

Children and families minister Nadhim Zahawi said: “The safety of children is paramount and any child going missing from home or care is of serious concern.

“We require all care placements to have clear procedures in place to prevent children from going missing. Local authorities must be informed if a child in care is missing – so they can take appropriate action.”

The cases behind the statistics

Caltu (not her real name) was 15 when she was trafficked from her home in Ethiopia to an Arab country. A wealthy family then brought her to London to work for them cleaning, cooking and looking after their children. “They were really abusive,” she said.

The family used a fake passport, which claimed Caltu was 29, to bring her into the UK.

She arrived at night in Heathrow and did not know what country she was in. She was met by her trafficker and immediately put to work. She could not speak English and had no relatives here. “I thought I am not going to have any life or future at all,” she said.

One day the son of the family tried to rape her, she fought him off and in the struggle he pushed her out of the window. She fell unconscious and when she woke up she asked around for help. A Somali lady, noticing Caltu had no shoes on, offered her help.

“It was so cold it was like winter,” said Caltu. “I had nothing on my body and she gave me some blankets and she took me in her car. She spoke to me in her language but I didn’t understand her. She took me to her home.”

Caltu ended up with the children services of a north London council. But they did not believe her age or story. “They told me I was an adult”. She was questioned for five hours as she had no evidence to prove who she was.

She was initially placed into semi-independent accommodation for young people while her case was decided. The decision of the council was then accepted and she was put in accommodation with adults.

During her stay in care she said “a lot of people just left because they were not believed”. She herself disappeared from care and was once reported to the police. “ I went missing, I go around and I came back”.

During that time she said she suffered from depression. “I had no school, no friends, nothing.”

ECPAT assisted her case to go to an immigration tribunal and she won. The council formally apologised to her for their treatment of her case. She has now been given accommodation and is currently at a further education college.

Jennifer was 16-years old when she was trafficked from her home in Ivory Coast. Her father told her he could no longer look after her so she was sent with a female relative on a flight to the UK. “She had all my documents, at the time I didn’t know what a passport was,” she said.

Jennifer remembers when she arrived at the airport that the woman made her stand behind her as they approached the immigration desk. She was then taken to a house. “As soon as I arrived I had to start working. Her husband was old and I had to care for him and clean the house. She would beat me if I did something wrong. One time she beat me so bad that I had to go to hospital because she hurt my eye”.

She had to accompany this woman to her local church and she got to know the pastor and the pastor found her a person who like her spoke French. “It was the pastor that started to speak to me, I told him everything that was happening and he called social services”.

“They came, but they just said I had to go back to the house and told auntie that she should not beat me. After that things got really bad she said that she was going to send me somewhere else, so I ran away. My pastor helped me again and took me to the police”, she said.

Jennifer was taken by a London council into accommodation for young girls. “It was very scary as I did not know these people and I could not speak the language. I was left there with no one checking on me”.

When she came into contact with social services they did not believe her story or that she was from the Ivory Coast. She was pregnant at the time and she was accused of lying about her story. “I was so stressed as social services had said before that they believed me. Now I was sacred they were going to throw me out”.

She found support in ECPAT and The Refugee Council who helped her with her case. “Now I am happy as I have my children and I am studying, but it has taken a long time to get here. Life in the UK as a victim of trafficking is so hard. You are very scared of your trafficker and you are not sure what will happen tomorrow. Will social services chuck you out? Will Home Office come and get you? Life is very scary and very stressful”, she said.

• This article was amended on 17 December 2018 to correct 276 to 246, which is 24% of 1,015.

Names have been changed to protect identities