“The Professional Teachers Union’s continuous twisting of the education minister’s words makes people wonder if they are trying to incite teachers’ emotions and promote their rally, as well as its political agenda,” the bureau’s spokesman said.

“The bureau has repeatedly explained the complaints process, but the union continues to twist facts and spread worry among teachers. It seems to be the one that is actually inciting white terror.”

The bureau accused the union, which represents about 85 per cent of teachers in the city, of a loss of professionalism, and said the government had a responsibility to follow up with every case of a teacher being charged, arrested or having complaints made against them to ensure the welfare of students, and maintain the standard of the education sector.

Teachers had every opportunity to appeal against any complaints made to the school authorities, the bureau said, and it would review reports made by the schools and strike down any unfounded complaints.

If wrongdoing was confirmed, the teachers would also be given the chance to submit a written explanation, the statement said, adding the process was fair.

“It is flatly spreading white terror,” said Fung Wai-wah, the union president. “The education sector is being scapegoated. The present crisis Hong Kong is facing is due to the government’s refusal to listen to the people’s views.

“But the government or the pro-establishment camp blame the teachers for encouraging students to take to the streets.”

Fung also said the union was planning to launch a crowdfunding campaign to raise money to help teachers facing suspension over their involvement in protests.

Friday’s rally is expected to last for two hours, starting from 7pm. A turnout of at least 5,000 is expected. Fung said representatives from overseas teachers’ unions would also attend to show support to their counterparts in Hong Kong.