A refugee charity urged the government yesterday to end the imprisonment of young asylum-seekers whose age is disputed.

There were a number of unaccompanied children still being imprisoned as they were wrongly thought to be adults, despite the government's 2010 pledge to end child detention, the Refugee Council said.

Last year 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 and two under 15.

The charity said it suspects the figures to be the "tip of the iceberg" with more cases of children being wrongly detained going unreported and unchallenged.

Refugee Council policy officer Judith Dennis said: "Locking up children who haven't committed any crime is a shameful practice that must end now.

"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.

It is also demanding that the government ensure 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."