The Refugee Council - which has a base supporting refugee children in Luton - is calling on Boris Johnson's government to change rules regarding refugee families.
Currently, adult refugees in the UK can sponsor family members to join them from abroad, but this is not case with child refugees.
The call comes as Amnesty International UK, Refugee Council and Save the Children release a 38-page report - Without My Family – which heavily criticises the UK government's policy on child refugees.
A petition urging the Home Secretary to change the rules has over 40,000 signatures.
Collin Ocaya, senior children's adviser at the Refugee Council’s Luton office, said: “Every day in Luton we see the destructive impact of the unfair rules that prevent refugee children from being reunited with their loved ones.
"The UK government could right this wrong in an instant, so far they have failed to do so.
"We urge the UK government to take notice of the key findings of this research and change its policy now, so that child refugees can be given the chance to grow up safe and secure with the people they need and love most.”
The UK is one of a handful of countries in Europe to prevent child refugees from sponsoring their family members to join them.
In 2018, MPs from across the political spectrum voted by a large majority to amend these rules. Despite this, the government has yet to implement changes.