Police have detained the head of a nationwide teachers union on charges of violating election laws.

The chairman of the Korean Teachers and Educational Workers Union, Won Young-man, was taken into custody Friday four days after he announced his support for the Democratic Labor Party.

Current election laws require civil servants, including teachers, to remain publicly neutral on election-related issues.

Police have also asked ten other union leaders to present themselves available for investigations but none have complied with the summons.

Three other union members were earlier taken into custody prior to Won' detention, including the head of the Seoul branch of the union.

The teachers?union has vowed to mobilize all means, including mass rallies to protest the police detention of union leaders.

The latest move was interpreted as a stern warning to civil servants' organizations that have expressed their support for the Democratic Labor Party, which they claim represents workers and the lower classes.