PHNOM PENH, Cambodia—Amid mounting losses from a nationwide strike, Cambodia's garment manufacturers warned of an extended hiatus in the country's key exports industry as workers continued pressing for higher wages over the weekend.

The job action—the largest this year in a sector plagued by frequent strikes—was launched last week by tens of thousands of workers seeking a higher minimum wage than what the government had offered. It has forced many factories to halt production, stoking concerns over widening fallout for this...