Hyundai Motor has said that twenty people were injured in a violent protest by hundreds of temporary workers.

The company said that the twenty permanent employees were injured in an attempt to drive out temporary workers who have occupied a Hyundai plant in Ulsan.

Riot police used tear gas to end a violent protest by hundreds of temporary workers inside and outside the factory and detained 50 demonstrators, Yonhap news agency said.

Some temporary workers were injured, it said.

The dispute began when a contractor took over the company's car seat production. Temporary workers have refused to sign contracts with the new company, demanding formal employee status.

Hyundai Motor said the latest protest had not affected its production.