Crushing of Strike Sparks Fierce Clash : South Korea: Twenty-four are hurt as workers battle police to protest an attack ending a shipyard sit-down. Other unions threaten action.

Thousands of angry workers battled riot police with firebombs, rocks, pipes and clubs Saturday to protest a huge police attack that crushed a three-day strike at the world’s largest shipyard.

Police said at least 24 people were injured, 10 of them police officers, in violence that began when thousands of security officials stormed the Hyundai Heavy Industries Co. by land and sea. Police said 499 workers were arrested and that warrants were issued for six fugitive union leaders.

The crackdown came as other plants threatened to stage sympathy strikes, raising fears of reduced business investment and more sharp declines in South Korea’s ailing stock market.

“The survival of the national economy was at stake,” a governing party spokesman, Park Hee Tae, said in defending the police action.

Opposition politicians demanded a parliamentary investigation of the attack, the second such action at the complex in a year. Protests broke out in the port of Ulsan, about 200 miles southeast of Seoul, and at least two other cities.

About 10,000 riot police stormed the closed shipyard at dawn to rout 2,000 workers. About 24,000 people work at the complex.

Police fired hundreds of tear-gas shells from at least 10 armored vans as bulldozers tore down nine-foot-high barricades erected by the workers. The riot police rushed in, wearing gas masks and helmets and carrying clubs and shields.

Hundreds of workers retaliated by throwing firebombs, steel bars, rocks and pieces of metal. Strikers fired several rounds from at least one of about a dozen homemade cannons, but it was not known if anyone was injured by the blasts.

About 600 combat police arrived in two patrol boats and surrounded buildings along the shipyard’s four-mile seafront. Three police helicopters hovered overhead, urging workers to surrender peacefully.

The fighting spread to the streets, where some estimates said up to 20,000 workers battled police. Television footage showed police kicking and beating some workers with clubs as they led them away to police vans.

Twenty-two police vehicles were damaged or destroyed, including two buses and five firetrucks, police said.

Authorities closed major roads in the area, suspended flights and canceled classes at 26 schools.

By nightfall, the sprawling seafront complex was quiet. Remains of burned workers tents, homemade weapons and rocks littered the grounds. Riot police guarded the five main gates, and black smoke and tear gas still hung in the air.

About 150 workers held out atop a 240-foot crane.

Leaders of the shipyard union said they would hold talks today to discuss strategy with workers from other Hyundai companies. They said 15 of 32 Hyundai company unions pledged to support the strike.

At the nearby Hyundai Motor Co., where protesters clashed with police in pitched street battles, workers in blue Hyundai jackets and red headbands stood guard at gates with clubs.

The Hyundai Group, owner of the shipyard and one of South Korea’s largest conglomerates, is the major employer in this city of 648,000, with well over 100,000 employees. Hyundai makes ships, cars, electronics, steel and other products.

Hyundai had requested government action to end the strike after negotiations broke down hours before. Workers demand the release from jail of four union leaders charged with starting earlier protests and obstructing work at the company.

Last year, about 12,000 police stormed the Hyundai shipyard to end a bitter 109-day strike.