The Federation of Korean Trade Unions(FKTU), one of the nation's two major umbrella unions has filed a constitutional complaint against an extension of a tax credit on union dues only to labor groups that publicize their ledgers.

At a press conference on Wednesday, the FKTU announced the appeal of related enforcement ordinances that took effect on October 1.

Through the ordinances under union and income tax laws, dues are eligible for a tax credit of up to 30 percent only if ledgers are publicized by April 30 each year by labor groups with members of one-thousand or more including affiliates.

FKTU said the ordinances extensively infringe upon the basic rights of unions and members of organization, equality and ownership while violating the constitutional order concerning principles of no taxation without law, legal delegation, and equality.

The umbrella group slammed the government for attempting to intervene in union management, incite opposition to unions and exclude unions from various state commissions.