A 17-year-old boy has died at Polmont Young Offenders Institute.
The Scottish Prison Service says Jonathan Beadle died on Saturday.
They have given no further details.
It comes two years after the government announced it would stop sending under-18s there.
A fatal accident inquiry will now be held.
A Scottish Prison Service spokesperson said: “Every death, whether in prison custody or in our communities, is a tragedy for all those who knew and supported the individual.
“Following the death of someone in our care, Police Scotland are advised, and the matter reported to the Procurator Fiscal. Fatal Accident Inquiries are held in due course.”
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