The network has produced a document called Managing Transitions from Secure Settings, which outlines problems with moving young people from secure children's homes back into the community.
The document lists examples collected from across the network where San alleges young people were not given the support needed to settle back into the community properly.
Roy Walker, acting chair of San, said a "distinct lack" of exit planning for young people needed to be addressed urgently and called for clear guidance on what is required when children leave secure care.
"We're also asking that as part of the future inspection process by Ofsted, it looks at making it a key area to be investigated," he said.
The document included the case of a 16-year-old young man from one secure children's home who was serving a three-year sentence for a serious offence.
When he arrived he had a reading age of an eight-year-old and was using drugs, but while staying at the home he received regular care from staff and achieved four GCSEs.
However, the report said on the day of his release the planned accommodation was not available and he had to sit in a local authority office for four hours before he was placed in a bed and breakfast several miles from his family. Within four weeks of living in the bed and breakfast, he had reoffended and was using drugs again.
A Youth Justice Board spokeswoman said the YJB is urging local authorities to ensure the rehabilitation work undertaken in custody is not lost when young people return to the community due to lack of support, accommodation and education. The YJB has invested directly in some rehabilitation services to support local work including the Resettlement Aftercare Provision programme.
