Rail and power workers in South Korea are extending their strike into a second day despite government threats to take stern measures against strike organizers.
On Monday helmeted riot police scuffled with union activists protesting some of the longest working hours in the world and a halt to the privatization of state utilities.
South Korean authorities have declared the strike illegal and say they are preparing to arrest its leaders, 36 of whom have taken refuge at a Roman Catholic church in central Seoul.
The government says Korean law bans strikes at public utilities.
As the standoff deepens thousands of riot police were deployed Tuesday morning at the campuses of Seoul National University and Konkuk University where an estimated 8,000 union activists are holding a sit-in.
Union officials have warned that 100,000 more workers will walk out Tuesday if labor laws aren't revised to meet their demands.
Workers at state-run Korea Gas ended their strike Monday, after agreeing a compromise with ministry officials giving unions a say on the timing and methods of the privatization process.
However, unions at several major Korean manufacturers, including Hyundai Motors, have threatened to join the walkout if demands are not met.

The militant Confederation of Trade Unions (KCTU), Korea's second largest union with some 500,000 members, said at least 100,000 workers would walk out at 1 p.m. local time unless labor laws are revised to ensure a five-day work week and flexible shifts.
Many South Koreans currently work a six-day week with long working hours.
Unions have said they fear mass layoffs will result from government plans to restructure debt-ridden state companies through privatization.
The sell-off of ineffective state firms is a key component of President Kim Dae-jung's economic reforms begun in the aftermath of the 1997-98 Asian economic crisis.
With the strike entering its second day those being hit hardest so far are commuters, facing lengthy delays with up to 50 percent of rail services cancelled.
A similar number of cancellations are expected Tuesday.
Freight services have also been hit with delays in the delivery of export cargo to South Korean ports.
However, the impact of protests by power workers has so far been limited because their facilities are mostly automated.