Northamptonshire County Council is looking after the fourth highest number of unaccompanied asylum-seeking children of local authorities in the UK.
A total of 4,210 children claiming asylum in the UK were reported as being in the care of local authorities as of March 31 2016, including 140 in Northants.
This was up 54 per cent on the previous year, according to new figures from the Department for Education (DfE).
The highest numbers were reported in areas where there are routes into the UK. Under government laws the local authority in which unaccompanied asylum seeking children arrive in the UK have a responsibility for their care until the youngsters reach the age of 18
Two-thirds of all unaccompanied asylum-seeking children were located in London and the South East, while a further 11 per cent were in the East of England.
A total of 865 children, roughly one in five of the total, were in Kent - the largest number for any local authority.
Croydon (430), Surrey (150) and Northamptonshire (140) reported the next highest figures.
The DfE said the rise in asylum-seeking children coming to the UK was the main factor behind an overall increase in the number of children starting to be looked after.
There were 70,440 looked-after children in England as of March 31 2016 - an increase of one per cent compared with March 31 2015 and five per cent compared with 2012.
The Chronicle & Echo reported last year that it costs Northamptonshire County Counci £4 million a year to look after the asylum-seeking children.
Cabinet member for vulnerable children at the county council, Councillor Heather Smith, (Con, Oundle) said the lack of foster carers in Northamptonshire also means the authority is having to pay carers in other areas to take the children in at grossly inflated costs.
She said: “The Government gives us some funding, but if we had plenty of foster beds in the county, that money would cover our costs.
“Because we are in a situation where we don’t have enough foster carers, we have to buy beds through agencies, which sends the price up.
“It’s putting a huge amount of additional pressure on us.
“But I have no issues with the children coming under our care. Many are 14, 15-year-olds who have travelled to England on their own and they need our care.”