Apple supplier Foxconn has denied forcing vocational school students in China to work at its factories.
A labor rights group has accused Samsung of "illegal and inhumane violations" at its factories in China, reporting cases of excessive overtime and exhausting conditions.
China's smartphone shipments surpassed those of feature phones for the first time ever during the second quarter.
Foxconn, a major supplier to Apple as well as other tech companies, has been steadily improving the working conditions at three of its Chinese factories following a February audit, according to the Fair Labor Association.
The number of lawsuits against Apple in China continues to grow: A Taiwanese man has sued the company, alleging that the FaceTime feature on its iPhone and iPad infringes on one of his patents.
A Samsung supplier in China allegedly employs workers under the age of 16, according to a labor watchdog group, which found the student workers earn about US$1 an hour.
A Taiwanese university has sued Apple for alleged patent infringement in its Siri voice assistant, in retaliation for patent disputes brought against Taiwanese firms by foreign rivals.
Apple's revenue for China saw robust growth in its fiscal third quarter, as iPhone sales continued to boom, even though the company delayed the launch of its new iPad in mainland China.
Apple's new iPad went on sale in China on Friday morning with a sparse, but orderly, line of people at one of its stores in Beijing, as the company used a new reservation system.
Apple stores in mainland China are using a reservation system this time around to launch the company's new iPad, which arrives in that country on Friday.
Apple has become the target of another lawsuit in China, this time because of its Siri technology, with a Shanghai-based company alleging that Apple has infringed on a patent involving its own personal assistant software.
A High Court in the UK has ruled that HTC did not infringe on Apple's photo management patent, while stating that three other patents Apple claimed in the lawsuit were invalid.
A Taiwan government office is warning local PC vendors of a new Apple patent for its MacBook Air that could be used in legal action to try and stop the sale of ultra book models.
According to a Chinese court, Apple has agreed to pay $60 million for ownership of the iPad trademark in China. This comes as part of a settlement with a little-known Chinese firm called Proview that had tried to ban sales of the tablet in the country.
Apple's repair policies have come under fire in China from a government funded consumer watchdog group, which has criticized the company for using refurbished parts to fix products.