Foxconn, which produces iPhones and iPads for Apple, has previously been accused of poor labour practices and working conditions.
The factory, in the city of Yantai in China's north eastern Shandong province, does not produce Apple products, but Apple has previously demanded that Foxconn maintains basic labour standards.
Employing vocational students as interns is normal practice in China, with as many as 10 million being used across the country at any one time.
However, Communications Director of the China Labour Bulletin, Geoffrey Crothall, says most are above the legal working age of 16.
Mr Crothall told Radio Australia's Asia Pacific that factories often need a cheap and flexible source of labour to meet demanding production targets.
He says students at the Yantai factory, which produces Japanese video game consoles, are made to work overtime and around the clock.
"They're not technically workers, they're covered by the labour law, they don't have an employment contract," he said.
"They are technically students but they're working in a factory, so they're actually in a very dodgy grey area."
Foxconn is the largest single provider of foreign investment in Shandong province, and according to reports, the city government of Yantai requires schools to send interns to its factory.
Mr Crothall says local governmnets "fall over themselves" to invite influential companies such as Foxconn to set up factories in their jurisdiction, and put pressure on local vocational schools to provide labour.
Foxconn says the violations occurred because Foxconn employees failed to check the ages of incoming interns.