BEIJING (AP) _ Most of the tens of thousands of workers who were striking at a massive Chinese shoe factory complex have returned to the job, labor activists said Saturday, enabling Adidas to resume production there.

The Germany-based athletic wear giant said workers returned Friday to its factory run by Taiwanese-owned Yue Yuen Industrial Holdings Ltd., the world’s largest manufacturer of athletic shoes.

More than 40,000 workers at Yue Yuen’s sprawling, multi-factory complex in the southern Chinese city of Dongguan went on strike in early April to protest underpayments into their social security and housing funds.

It was one of the largest strikes ever in China’s private sector, where low-cost manufacturers are facing increasing labor activism amid a shortage of migrant workers, pushing up labor costs.

Yue Yuen makes shoes for major brands including Adidas, Nike and New Balance, which are increasingly looking to other countries to source their production.

Labor activists confirmed Saturday that most Yue Yuen workers, including those assigned to the Adidas factory, had returned to work, though about 10,000 remained on strike.

The workers have not reached a deal with Yue Yuen, which has offered to pay full contributions starting May 1. The company rejected workers‘ demands for a 30 percent pay raise and back payments into their social security funds.

It was unclear why most of the workers had returned to the job. Some labor activists said Yue Yuen management _ assisted by police _ forced the workers to return.

It was not immediately known whether Nike or New Balance had resumed production at Yue Yuen.

On Wednesday, Adidas said it was moving some of its production from Yue Yuen to other suppliers. But as production at Yue Yuen resumed Friday, Adidas said in a statement that it remained committed to Yue Yuen and “to China as a sourcing country.”