Inmates at a prison in China were "forced" into gold farming, respectable British newspaper The Guardian has reported. 300 people at one particular prison were made to collect virtual currency in online games, to be sold for real money to people who didn't want to gather it themselves.

"Prison bosses made more money forcing inmates to play games than they do forcing people to do manual labour," Liu Dali, a pseudonymous former prison guard who was jailed for three years in 2004, told The Guardian. "There were 300 prisoners forced to play games. We worked 12-hour shifts in the camp. I heard them say they could earn CN¥5,000-6,000 [$770-925] a day. We didn't see any of the money. The computers were never turned off."

"If I couldn't complete my work quota, they would punish me physically. They would make me stand with my hands raised in the air and after I returned to my dormitory they would beat me with plastic pipes. We kept playing until we could barely see things," Liu said.

Gold farming, if you've had the astonishing fortune to never come across it, is simply the process of repeating money-making routines in online games over and over. It might be by collecting and selling crafting materials, or simply killing and looting monsters for hours on end. This virtual currency, 'gold,' is then sold for real money to players who don't fancy collecting it themselves. While many online games expressly forbid gold farming, such as World of Warcraft, some, like EVE Online have built-in authorised ways for players to convert cash money to virtual space dollars. WoW developer Blizzard has itself sued, and won against, a gold farming company.

For players who spend their money on farmed gold, it's a convenient way to avoid the tiresome grind that's built into most MMOs. For many legitimate players, though, gold farming is seen to artificially inflate the game world's economy, driving item costs up as players with farmed gold happily pay prices that'd take yonks of playtime to afford otherwise.

While the gold farming industry is by its nature impossible to accurately track, one 2008 study estimated it to be worth $500 million annually. Three years is a long time in the world of MMOs, so doubtless that figure would be even greater today.

The dark side of gold farming has been known for some time now. While the practice began on a small scale, with players selling between themselves, it soon became industrialised and outsourcing began, with many farmers working in conditions markedly less pleasant than a cosy bedroom in the USA. The study in 2008 estimated that, at the time, 80% of gold farmers were in China.

Liu suspects the practice hasn't ended, though a 2009 Chinese law was supposed to crack down on selling virtual currencies, making it illegal for anyone but legitimate business with licenses. "Many prisons across the north-east of China also forced inmates to play games," he said. "It must still be happening."