Eight out of the 13 Vietnamese teenagers who disappeared from a county council's care more than a year ago are still at large, police have confirmed.
The group absconded after they were discovered in the back of a lorry in Corby, Northamptonshire, in June 2017, having entered the UK illegally.
A year after police issued an appeal, only five of the young people, aged between 15 and 18, have been located.
Northamptonshire County Council said it was "very concerned" for their welfare.
A spokesman for the authority said: "There are particular concerns about these young people due to the circumstances of their arrival, given the fact that we had very little time to assess their needs when they came into our care before they went missing."
The three girls and 10 males were looked after by Northamptonshire social services after they were found in the lorry on a Corby industrial estate on 17 June, 2017.
They then disappeared "one after the other" from accommodation in Northampton and Corby where they had been safeguarded, police added.
Eight boys remain at large after leaving properties separately in June, July and September 2017.
Police have not commented on whether the youngsters were trafficked or entered the UK of their own free will.
The teenagers, who are all missing from addresses in Northampton, are:
- Quang Dang Le, 16, 5ft 5in (1.65m)
- Ha Van Le, 18, 5ft 7in (1.70m)
- Ha Van Nguyen, 17, 5ft 6in (1.66m)
- Trong Nguyen, 17, 5ft 4in (1.62m)
- Binh Van Hoang, 18
- Khoa Anh Yu, 15
- Lihn Van Nguyen, 16
- Quang Trong Nguyen, 17, 5ft 1in (1.55m)