Foxconn, Apple's top manufacturer, has improved safety conditions and cut working hours in an effort to resolve violations at its plants that triggered a global scandal for the iPad and iPhone maker.

The Taiwanese company submitted to an audit by an independent group, the Fair Labor Association (FLA), after reports of suicides and abusive conditions at several of its factories in China.

Tim Cook, Apple's chief executive, asked the FLA to investigate after a series of reports into working conditions at Apple's key supplier. In February and march the FLA found at least 50 violations of local regulations at Foxconn plants in Chengdu, Guanlan and Longhua.

The FLA said Foxconn had made significant improvements such as introducing more breaks and better maintenance of safety equipment. The company more than doubled wages after protests from worker groups and is backing a local law adjustment that will extend unemployment insurance.

Foxconn had completed all the 195 actions that were due at the time of the FLA's report and another 89 action items were completed ahead of their deadline, according to the FLA. Another 76 actions are due over the course of the next year.

But the FLA said Foxconn faces more challenges in the coming months. Foxconn has reduced hours to under 60 per week including overtime and is aiming to reach full compliance with the Chinese legal limit of 40 hours per week plus an average of nine hours of overtime per week.

"The next phase of improvements will be challenging for Foxconn because they involve major changes in the working environment that will inevitably cause uncertainty and anxiety among workers. As Foxconn prepares to comply with the Chinese legal limits on work hours, consultation with workers on the changes and implications will be critical to a successful transition," said FLA president Auret van Heerden.

Foxconn is the world's biggest electronics contract manufacturer. As well as being Apple's largest supplier Foxconn, which employs about a million people, makes products for Sony, Hewlett-Packard, Cisco Systems and others.

Criticism of the company has been mounting for years. In 2009 a 25-year-old worker committed suicide, reportedly after losing an iPhone prototype. After a spate of suicides Foxconn installed nets around the edges of some buildings to prevent people jumping off roofs.

In January following a New York Times article that documented problems inside its supplier factories Cook emailed staff worldwide to say: "we care about every worker in our worldwide supply chain. Any accident is deeply troubling, and any issue with working conditions is cause for concern. Any suggestion that we don't care is patently false and offensive to us."