Apple supplier Pegatron reported that an explosion occurred at a subsidiary company in China, with Shanghai authorities stating that 61 workers were sent to hospital.

The December 17 explosion occurred at a Shanghai factory operated by RiTeng Computer Accessory, which lists PC makers HP, Dell and Asus among its clients. Shanghai authorities said that 27 employees were required to stay in the hospital for observation, but none had life-threatening injuries.

The explosion resulted in damage to a minor part of the factory's automation equipment, Pegatron said in a statement to the Taiwan Stock Exchange. The damage will have minimal effect on the factory's operations, it said.

The cause of the explosion is still under investigation, but preliminary results suggest it was caused by aluminium dust.

A receptionist at Pegatron said that the company was not available for comment at this time. RiTeng was also not available for comment.

Earlier this year, another Apple supplier Foxconn also reported that an explosion occurred at a factory in Chengdu, killing three workers. The company said the explosion was caused by "combustible dust in a duct."