When the reoffending rate was introduced as an important factor in the evaluation of prisons in 2008, the Bureau of Prison Management introduced a range of courses designed to help ex-inmates stay on the straight and narrow when they re-enter society.

Classroom education is now mandatory in all prisons, and inmates are offered courses in legal and cultural studies, psychology and technology.

Every prison must ensure that prisoners spend two months studying the law to ensure that they cannot use ignorance as an excuse for their wrongdoing.

The regulations also require a mental health center to be set up in every prison across the country, and more than 30,000 professionals work in the field of psychological rectification, according to the bureau. By the end of 2012, about 170,000 prisoners had been provided with one-on-one consultations.

The bureau has worked with the Ministry of Education to compile teaching materials, and every prisoner is expected to attain at least the equivalent of a primary school education - basic literacy and numeracy. They are allowed to sit national-level exams for skilled workers, and if they pass they are issued with certificates that will make it easier for them to find work when they have served their time.

At the end of 2013, China's prisons held about 1.8 million prisoners, according to the latest statistics issued by the bureau.