South Korean workers clashed with riot police at a May Day rally in Seoul on Friday, vowing to wage an "all-out general strike" if the government pushes through with planned labour reforms.
Thousands of riot police erected barricades to block about 10,000 workers from marching toward the office of President Park Geun-Hye.
The police fired water cannons laced with a chemical irritant in scattered clashes with some marchers who tried to force their way through barricades in a tense three-hour standoff on the roads leading to Park's office.
Park's administration is seeking to push through a reform plan that it argues would introduce flexibility to a rigid labour market, by making it easier to hire and fire.
"We will crush any government attempts to suppress labour rights with an all-out general strike," Federation of Korean Trade Unions head Kim Dong-Man told the crowd at a rally near parliament.
Elsewhere in Asia, dozens of protesters in Taiwan threw smoke bombs near the presidential office during a workers' rally, while in Hong Kong domestic helpers were out in force to seek greater rights.
Hundreds also gathered in downtown Manila to press for higher wages and more job opportunities at home, to prevent so many Filipinos heading overseas, often into vulnerable situations or outright danger.