A refugee charity has urged the Government to end the imprisonment of young asylum seekers whose age is disputed.
A number of unaccompanied children are still being imprisoned as they are wrongfully thought to be adults, despite the Government's 2010 pledge to end child detention, the Refugee Council said.
In 2013 the charity secured the release of 36 young people found in detention who had been wrongly assessed to be adults. Six other young people have been released from detention into local authority care pending a new age assessment.
Of the young people released, 12 were under the age of 16, with two being under the age of 15.
The charity said it suspects the figure to be the "tip of the iceberg" with more cases of children being wrongly detained going unreported and unchallenged.
Asylum seekers who are having their age disputed are frequently jailed in adult immigration centres, forced to share a room with adults, the Refugee Council said.
Refugee Council policy officer Judith Dennis said: "Locking up children who haven't committed any crime is a shameful practice that must end now.
"The Government knows that wrongfully imprisoning vulnerable children can cause lasting psychological and emotional damage so it's completely astounding it continues to do so.
"Children within the asylum system are already extremely vulnerable. It's wholly unacceptable that they are consistently put at further risk by the authorities who are supposed to be protecting them. Children should be treated as children first, regardless of their immigration status."
The Refugee Council is calling for people whose age is in question to be given the benefit of the doubt until their age has been carefully established by an independent professional.
The charity is also calling for the Government to ensure that each asylum seeking child is appointed a legal guardian.
Ms Dennis added: "Now is the time for the Government to live up to their pledge to end child detention once and for all."