The government plans to implement labor laws next year allowing multiple unions for each workplace and banning companies from paying wages to full-time union representatives. The laws were passed in 1997 but have never been implemented because of opposition from labor unions.

About 4,600 workers staged a rally criticizing the government's plan in a plaza near the National Assembly on Sunday, according to police. Tens of thousands rallied Saturday at the same site.

"The government's policies are intended to stifle labor unions," said Lee Su-bong, a spokesman for the 800,000-member Korean Confederation of Trade Unions, a major umbrella labor union that organized Sunday's rally.

About 14,000 police officers were mobilized to maintain order, and the rally was peaceful. Protesters held a banner calling President Lee Myung-bak a "swindler" and listened to speeches by union leaders.

On Saturday, another major umbrella union _ the 900,000-member Federation of Korean Trade Unions _ also staged a peaceful demonstration. Police estimated about 60,000 people attended.

Both labor unions have said they would launch a large-scale strike if the government doesn't cancel its plans to enforce the laws.

Calls to the Labor Ministry seeking comment were unanswered Sunday.