China's Yue Yuen Industrial Holdings, the world's largest sports shoe maker, said on Wednesday that thousands of workers at a factory in the south of the country have gone on strike following changes to production processes.

About 4,000-5,000 staff at Yue Yuen, which supplies footwear for Nike Inc and adidas AG, were protesting at facilities that produce shoes for international brands, said Jerry Shum, the firm's Hong Kong-based investor relations director. He didn't identify the brands supplied by the plant.

The company was in control of the situation and expected it to be resolved in a few days, Shum said.

He noted the strike, by workers representing about 2-3 percent of Yue Yuen's staff in China, had no impact on Yue Yuen's production schedule so far.

"Due to changes in the economic environment, we need to reorganize some of the production," Shum said. "As a consequence, workers were not very happy to see the change in the production... and that led to some disagreement."

A New York-based labor NGO said the workers were demanding an immediate payout of their housing fund following a move to merge two plants. Shum declined to confirm this.

In 2014, tens of thousands of workers at Yue Yuen, which has a market value of $6.5 billion, called off a strike after the footwear maker pledged to meet some of their demands.

Major manufacturers have been shifting some of their production away from China to other Asian countries, such as Vietnam and Indonesia, as labor and production costs escalate.

Yue Yuen said the reorganization of its production process was being driven by the economic environment and it was trying to offer more options to cost-sensitive customers.