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About 30,000 children in care live outside their local area, with nearly 12,000 placed 20 miles or more from friends and family, a report suggests.

It says 2,000 are housed more than 100 miles from wherever they call home.

A growing number are isolated from support and at increased risk of going missing, says children's commissioner for England Anne Longfield.

The government says children are moved away only as a "last resort", with "safety and suitability" the priority.

According to the Department for Education, there were 78,150 children in care at 31 March.

The commissioner's report, titled Pass the Parcel, identifies a 13% increase in the number of minors housed outside their English local authority area over four years.

A rise in numbers of older children in care has also left cash-strapped councils without enough suitable places locally, meaning many end up in privately run children's homes in cheaper areas but without the family structure of a foster place, it adds.

"Some children in care have told me they feel like parcels - passed from pillar to post, unsure where they even are on a map," Ms Longfield said.

"We wouldn't want this for our own children, and we shouldn't accept it either for those children who rely on the state to look after them."

The post of children's commissioner for England was created to act as an independent representative of young people, with the aim of influencing policy that affects them.

What teenagers told the commissioner

"I feel like a parcel getting moved around all the time" - girl, more than 100 miles from home

- girl, more than 100 miles from home "I'd never heard of this area" - boy, 75 miles from home

- boy, 75 miles from home "I feel isolated. I don't even know where I am… you feel like you have no-one" - girl, in care

- girl, in care "I don't even know where I am on the map" - girl, 80 miles from home

- girl, 80 miles from home "I never unpack 'cause I know I'll be passed on somewhere else in a few weeks" - girl in care

Source: Pass the Parcel, children's commissioner for England

The report says the London boroughs of Westminster, Hammersmith and Fulham, and Tower Hamlets send the most children out of area.

It acknowledges some need to be moved owing to the risk of violence, sexual predators or of being groomed by gangs, but says a lack of suitable council places is often the reason.

Mark Russell, chief executive of charity the Children's Society said: "It is simply not good enough that so many of these vulnerable children are being placed because that is where a bed is free and not because that is where the child is most likely to receive the care, support and sense of belonging they deserve."

Ms Longfield is calling for an independent review into the children's social care system, in particular looking at their emotional and safety needs.

A government spokesman said placements were approved by local authority children's services directors and that Ofsted would challenge poor decisions.

"We know there are challenges in finding the right placements, and we've already pledged an extra £1.5bn for child and adult social services, as well as a review of the system so children receive the best possible care," he said.