Nintendo is investigating Wii U manufacturer Foxconn after it admitted to using child workers in a Chinese factory.

Foxconn confessed to illegally hiring the workers, some as young as 14, to cover a shortfall in its regular staff during Wii U production. Chinese law states the legal working age as 16.

"Our investigation has shown that the interns in question, who ranged in age from 14 to 16, had worked in that campus for approximately three weeks," Foxconn admitted in a statement to Reuters.

"This is not only a violation of China's labour law, it is also a violation of Foxconn policy and immediate steps have been taken to return the interns in question to their educational institutions."

Earlier reports in the Chinese media (via Kotaku) suggested that the children had been forced to work at the plant for extra school credit. They were told they faced expulsion if they quit.

"If you don't intern, then you won't get any credit, won't receive a graduation diploma, or may even be kicked out of school," students were instructed, according to China Labour Watch.

The young workers were not necessarily limited to Wii U production, but initial reports named the Wii U as a device they worked upon.

Nintendo has responded with a short statement to confirm it was investigating the issue.

"We take our responsibilities as a global company very seriously and are committed to an ethical policy on sourcing, manufacture and labour." Nintendo

"Nintendo is in communication with Foxconn and is investigating the matter," a spokesperson said (thanks IGN). "We take our responsibilities as a global company very seriously and are committed to an ethical policy on sourcing, manufacture and labour.

"If we were to find that any of our production partners did not meet our guidelines, we would require them to modify their practices according to Nintendo's policy."

It is the latest damning report of conditions at Chinese manufacturer Foxconn, which has repeatedly hit the headlines this year for trouble on its iPhone and Xbox 360 production lines.

Controversies have included high rates of employee suicide, a threat of mass suicide, strikes over appalling working conditions and a recent riot that left up to 40 in hospital when security forces intervened.