Staff at a home for children who have suffered abuse or trauma held door handles closed to contain aggressive behaviour, according to a watchdog.
The home, which cannot be named for legal reasons, was rated “inadequate” in all areas when it was inspected by Ofsted this month.
Another Suffolk County Council-run home for vulnerable children has also recently been given the lowest rating.
The authority said it was “acting swiftly” to address the issues.
Conservative-run Suffolk County Council manages five homes for vulnerable children.
The other three are currently rated as “good”, according to the Local Democracy Reporting Service (LDRS).
The latest Ofsted report said behaviour management techniques at the home were unsafe and did “not respect children’s rights and dignity”.
It said there was a “significant increase” in the number of physical interventions, and staff resorted to holding bedroom door handles closed to contain some children’s aggressive behaviour.
The council said there was not a systematic issue with how it was running the homes.
Allan Cadzow, service director for children and young people, said: “We take the findings of the report extremely seriously.
“We have taken immediate action to end the practice Ofsted identified and are acting swiftly on the recommendations made.
“Senior managers will be ensuring all necessary action is taken to ensure the children’s home returns to its previous status of ‘good’ as soon as possible.”
Labour education spokesman Jack Abbott said he was “deeply concerned”.
He said: “This is a devastating report and the brutal truth is that, as the corporate parent of these vulnerable children, Suffolk County Council is ultimately responsible.”