Apple supplier Pegatron Corp reported an explosion at a subsidiary's plant in Shanghai over the weekend that it said had injured 61 workers. The explosion on the plant, which belongs to Riteng Computer Accessory Co, had not caused a fire, but 23 of the injured workers needed to be hospitalized, according to a Reuters report.

Pegatron said that there was also some damage to machinery but it could make adjustments to the facility to minimize the impact on operations and revenue.

Safety concerns over factories in China and especially over Apple's supply chain, have come under criticism from the Chinese government, and labor and environmental groups.

Hon Hai Precision Industry Co Ltd, Apple's top manufacturing partner, has had two incidents at China plants this year.

Last August, Chinese environmental organizations said 27 companies thought to be Apple suppliers had severe pollution problems.