Updated

An international human rights group says that Thailand's prisons fail to meet international standards, with inmates routinely shackled, stuffed into overcrowded cells and forced to work in harsh conditions.

The report issued Tuesday by the International Federation for Human Rights says Thailand also has the highest incarceration rate in Southeast Asia, jailing 425 out of every 100,000 people.

There are more than 260,000 inmates in 148 prisons with an originally estimated capacity of less than 120,000, the report said, with the massive overcrowding forcing the inmates to live in harsh conditions.

Most inmates were convicted on drug-related charges, the legacy of a war on drugs launched by former Prime Minister Thaksin Shinawatra in 2003.