Any significant industrial strike could mar a good chance for the Korean economy to improve further, helped by the World Cup

Lee Kyoung-shi School teacher "

A series of strike actions which could last for several days was kicked off when 31,000 metal workers and chemical employees staged a four-hour strike over pay and working hours.

The militant Korean Confederation of Trade Unions (KCTU) refused to rule out action during the football tournament which South Korea and Japan are co-hosting from 31 May.

"This is an indefinite strike. We'll fight until an agreement is reached at all work sites," said union leader Han Sun-joo.

National pride

President Kim Dae-jung has called on the workers to return to work, at least until the World Cup is over.

Many agree with him.

"This is not the right time," said school teacher Lee Kyoung-shi.

"Any significant industrial strike could mar a good chance for the Korean economy to improve further, helped by the World Cup.

"The Cup should not be held hostage."

The strike action was launched just as the International Monetary Fund said it might upgrade its 5% economic growth prediction for the country.

"Korea would be a case where, from what we've seen, the upward revision could be quite large," said the Fund's deputy director for Asia Pacific, Charles Adams.

South Korea's economy grew 5.7% during the first three months of this year, according to official figures.

Tough action

On Tuesday, the prime minister's office warned that "the government will deal sternly with illegal strikes and collective actions which could undermine the country's image during the World Cup".

South Korea's 10 World Cup stadiums and the players' hotels will be cordoned off.

And anti-terrorist security forces are expected to be positioned in the roof of stadiums, ready to abseil onto trouble makers.

Taxis to strike?

Unions said strike action could spread to involve up to 70,000 workers including hospital staff, metal and chemical workers and up to 12,000 taxi drivers.

Officials have accused the unions of taking advantage of the football event to press their case.

They have said they will examine union calls for a shorter working week and improved working conditions positively - but that any other demands will only be discussed after the football finals.

A union federation has accused the government of cracking down on union activities.

Hotel workers have agreed not to strike - at least until the tournament is over.

Korean trade unionists have held a series of illegal strikes since late February, when power workers leaders began a cathedral sit-in to protest against privatisation.