"As of today, the factories are shut down indefinitely," a Hyundai spokesman said.

A Hyundai statement on Friday said that the company had no choice to take such action "as normal operation has been impossible" due to the union workers, demanding no worker be fired despite economic difficulties.

"We have done our best to reduce the number of workers to be laid off, and as of August 12, we have brought down the number to 615. But the union refuses to make any compromises, and continues to insist no layoffs," it said.

Hyundai on Monday reopened the Ulsan car plants, crippled since July 20 after union workers downed tools over the company's decision to sack over 1,500 workers.Company officials including chairman Chung Mong-Kyu have tried to get the factories running since they reopened this week, but was stopped by unionworkers.

Hyundai said a total of 127 officials have been hurt by union workers resorting to violence."We again urge the union to help us resume normal operation as soon as possible," the Hyundai statement said.

Hyundai recently said it had lost about 610 billion won since the Ulsan car plants closed on July 20.