The moves are supported by an EU policy that says child asylum seekers can only be deported if reception centres are created to care for minors when the family cannot be found.
But Donna Covey, chief executive of the Refugee Council, said the plans did not say how children would be kept safe once back in Afghanistan.
"It really begs the question: if they have no family to whom they can be returned safely, should they be returned at all?"
"There are serious questions to be raised about the quality of decision-making on the cases of unaccompanied children.
"Going back to Afghanistan means either death or a long imprisonment for me, because I was tortured by authorities"
Yusef, asylum seeker in the UK
"The money would be better spent improving the way that children's claims are assessed, so that we can be sure we never put them in danger," she said.
Yusef, a young asylum seeker in the UK, told Al Jazeera that he feared torture if he returned to Afghanistan.
"Going back to Afghanistan means either death or a long imprisonment for me, because I was tortured by authorities," he said.
"If I return it will be easy for them to identify me and I'll be subject to that torture again. As a result I'll either die or be imprisoned."
Caroline Slocock, chief executive of Refugee and Migrant Justice, said that children had often endured long and dangerous journeys to Britain, and sending them back to Kabul would only put "their safety and welfare further at risk".
Human Rights Watch has challenged the decision, writing to the Norwegian government earlier this year about what procedural guarantees it will provide to ensure a child's return is in his or her best interests.
Tom Porteous, the director of Human Rights Watch in London, said European government were presuming that the children's best interest would always be best served by sending them back to Afghanistan.
"That simply can't be the case," he told Al Jazeera.
"Many of these children are actually not coming from Afghanistan. They're of Afghan by origin but many of them have been living in Iran or Pakistan so their families are not in Afghanistan.
"In many cases they're fleeing from very serious conditions ... A lot of children are facing abuse. Many of them have arrived in the European Union as a result of human trafficking so these people are very vulnerable and in each case there needs to be a thorough assessment of their needs."
Many Afghan asylum seekers arrive in Britain via smuggling channels and overland journeys on trucks, Peter Kessler from UNHCR, the UN refugee agency, told Al Jazeera.
According to Britain's home office there are approximately 4,200 unaccompanied child asylum seekers in the country, with those from Afghanistan making up the largest group.
Damian Green, the UK's immigration minister, said the proposed centre was part of a policy to discourage Afghans from making "dangerous journeys across the world".
"We are looking to work with other European countries, such as Norway, and valued international partners, such as Unicef, as well as the Afghan government to find ways to help these young men in their home countries and to return those who are in the UK safely to their home nations with appropriate support once they arrive," he said.
The decision could mark a change in British policy, with the number of deportations previously limited due to child protection issues and care arrangements for minors.