A left-leaning teachers’ union filed a petition against the government Wednesday, protesting its decision to press charges against participants of an anti-government rally.

The rift between the Education Ministry and the Korean Teachers and Education Workers’ Union, recently outlawed for a violation of the labor law, has been widening since the latter lost its legal status in June.

The Education Ministry recently filed charges against scores of members of the KTU that were in charge of a June rally which demanded President Park Geun-hye take responsibility for the fatal ferry sinking in April and step down.

KTU members who organized a joint-statement ― in which more than 10,000 teachers across the country participated ― also faced charges.

“Both the statement and participating in the rally should be respected as a freedom of speech. The government seeking to punish the teachers is basically a demolition of democracy,” the KTU said in a press conference, after filing a petition with the National Human Rights Commission of Korea.

Korea’s National Public Servant Law bans teachers from taking politically motivated collective action or voicing their political opinions in public.

“It is an act of oppression against the freedom of speech entitled to teachers regarding the Sewol (ferry) tragedy. The KTU will continue our struggle,” KTU spokesman Ha Byung-soo said.

Teachers reading a statement about the Sewol tragedy and expressing their opinion to the public does not mean they neglected their role as a teacher, he said.

A petition to a United Nations special rapporteur was also filed Wednesday, he added, and the group will also take the case to the International Labor Organization within this week.

The ILO has already criticized the government’s decision and made it clear that allowing retired and dismissed workers to become union members and leaders was internationally accepted.

“We expect the ILO to discuss the issue with great significance in its general meeting in November,” Ha said.

Education International, a global federation of teachers’ trade unions, also backed the KTU in a recent statement and urged the government to “respect international labor standards” and re-certify the group.

While the KTU continued its all-out struggle against the government, authorities pushed forward with the investigation into what it called “illegal political activity” by KTU members.

Officers from Seoul’s Jongno Police Station raided the KTU office for the second day on Wednesday and confiscated servers containing online posts and e-mails written by its members from May 1 to July 2.

Police said they were assessing the data to see if KTU teachers had broken any law while participating in the June rally and the joint-statement. The KTU denounced the move calling it “collaborated oppression from the prosecution, the Education Ministry and the presidential office of Cheong Wa Dae.”

By Yoon Min-sik (minsikyoon@heraldcorp.com)