Tens of thousands of workers in South Korea went on strike on Tuesday, crippling airline services and other major industries.
"If we cannot restore social order, foreign investors will stop investing in Korea"
President Kim
Defying warnings of a crackdown by the government, the workers walked out of their workplaces demanding higher pay and for the government to abandon its economic restructuring programme, which has led to thousands of job losses.
President Kim Dae-jung has declared the strikes illegal, and warned they were a threat to social stability and global competition, saying investors would turn to China and south-east Asia instead.
Flights were cancelled at Seoul's Kimpo airport
"We will become a loser overnight in global competition if we stop restructuring," he said in a statement.
President Kim said the government would deal sternly with the illegal walkout and any violence.
State prosecutors have already warned they were taking steps to arrest leaders of the Korean Air pilots' union.
Flights grounded
Some 50,000 unionised workers at more than 120 factories joined the protests, according to the Korean Confederation of Trade Unions, a militant nationwide labor umbrella group.
However, the government claimed the numbers to be significantly less, saying disputes were being resolved at dozens of locations through last-minute negotiations.
Workers remained defiant, despite government warnings
Thousands of staff from Korean Air and the domestic airline, Asiana, joined the strike, forcing Korean Air to cancel 60% of its international services.
Korean Air said about 80% of its fleet would inevitably be grounded.
Militant South Korean unions in metal, chemical and heavy industrial companies also downed tools.
The nationwide strike could escalate with hospital workers at large hospitals vowing to join the walkout on Wednesday.
The KCTU, which claims 500,000 members, is also demanding the government allow a five-day workweek and improve working conditions for non-regular workers.
South Korea is still recovering from the 1997 Asian financial crisis, which forced the country to accept a $58.35bn rescue package of the International Monetary Fund.