A Ministry of Justice source said that 37 people were released in error on 10 September, because their offences were wrongly logged under outdated legislation.

Five prisoners have not yet been returned to jail but most have been brought back into custody.

The mistake was made because the prisoners were sentenced under outdated legislation.

A Ministry of Justice spokesperson said: "Public safety is our first priority. That is why we took decisive action to fix the broken prison system we inherited and keep the most dangerous offenders locked up.