The union at Kumho Tire, South Korea's second-biggest tire maker, said Wednesday that it has decided to stage an indefinite walkout after no headway was reached on a wage deal with management.

The strike, scheduled to start Thursday, comes just two days after the union ended a month-long partial walkout by 3,100 workers to iron out wage and other outstanding differences.

Sources said that some gains were made in areas related to human resources management and giving workers greater say in the company's decision-making progress. They, however, said differences were wide over wages.

"Workers are angry at the decision by the company to raise wages for executives by 15 percent while asking for sacrifices from workers," a union representative said.

Unionists have demanded a 13 percent pay hike with management countering that it can only accept a temporary hike in bonuses. The company also made clear it could not cancel a comprehensive wage cut deal reached in 2010 that sets salary guidelines.

Meanwhile, Kumho said that it has lost 100 billion won (US$88.5 million) in production since the labor protests began on July 10. (Yonhap News)