A massive worker strike over unpaid social benefits in Guangdong province has exposed loopholes in the country's social security system and illustrates the growing pressure on manufacturers to stay ahead of rising labor costs.

The strike at Yue Yuen Industrial (Holdings), a Dongguan-based producer for major brands including Nike, Adidas and Timberland, entered its third day.

About 600 workers first stormed onto the streets on April 5, blocking roads and demanding that social insurance and housing funds be fully paid.