Apple, following reports of harsh working conditions, said a labor watchdog group began inspections on Monday at a Foxconn plant in China that makes products for the California gadget-maker.
"We believe that workers everywhere have the right to a safe and fair work environment, which is why we've asked the (Fair Labor Association -- FLA) to independently assess the performance of our largest suppliers," Apple chief executive Tim Cook said in a statement.
"The inspections now underway are unprecedented in the electronics industry, both in scale and scope," said Cook, who took over as chief executive last year from Apple's late co-founder Steve Jobs.
Apple agreed last month to allow inspections by the independent labor watchdog following reports that employees were overworked and underpaid at Foxconn factories in China.
The Taiwan-owned Foxconn is the largest manufacturer of Apple products.
Apple said the first inspections began Monday morning at a massive facility in Shenzhen known as Foxconn City. They were carried out by a team of labor experts led by FLA president Auret van Heerden.
Apple said the FLA will "interview thousands of employees about working and living conditions including health and safety, compensation, working hours and communication with management."
"The FLA's team will inspect manufacturing areas, dormitories and other facilities, and will conduct an extensive review of documents related to procedures at all stages of employment," the company said.
The Cupertino, California-based Apple said its suppliers have pledged "full cooperation with the FLA, offering unrestricted access to their operations."
Apple said the FLA's findings and recommendations will be posted on its website, fairlabor.org, in early March.
Besides Foxconn plants, FLA teams will also inspect factories owned by two other Taiwan-owned manufacturers, Quanta and Pegatron, which also make Apple products.
"When completed, the FLA's assessment will cover facilities where more than 90 percent of Apple products are assembled," Apple said.
Apple joined the FLA last month and divulged for the first time a list of its suppliers.
Last week, petitions were delivered to Apple stores in several countries denouncing working conditions at Chinese factories making Apple gadgets.
Mark Shields, organizer of a Change.org petition that attracted over 200,000 signatures, welcomed the opening of factories in China to outside audits.
"As an Apple consumer, I'm relieved to hear that Tim Cook is taking this seriously and breaking ground in the industry with Fair Labor Association auditing," Shields said in a statement.
"But Apple still needs to use some of their trademark creativity and problem solving to create a worker protection plan for new products -- especially the upcoming iPad 3 -- so that they're proactively taking care of their workers."
In 2010, Apple was accused of abetting poor worker conditions after a rash of worker suicides at Foxconn's plant in Shenzhen, a southern boomtown on the border with Hong Kong.
The New York Times reported last month that workers assembling iPhones, iPads and other devices at Foxconn facilities in China "often labor in harsh conditions" and work "excessive overtime."
According to the newspaper, two explosions at iPad factories last year killed four people and injured 77.
The recent criticism of working conditions in China has done little to dent Apple sales and shares of the company surged past $500 for the first time on Wall Street on Monday to close at $502.60.
Apple reported blockbuster quarterly earnings last month with net profit more than doubling to a record $13.06 billion and revenue soaring to an all-time high of $46.33 billion.
Shares of Apple have been rising steadily on the release of a string of hit products starting with the iPod in 2001, followed by the iPhone in 2007 and the iPad in 2010.