A Hong Kong teacher has been struck off for allegedly promoting the city's independence in class, in what the government on Tuesday hailed as a blow against "black sheep" working in the education system.
The decision is the first time Hong Kong's Education Bureau has removed a teaching licence because of the content of lessons, and comes as a crackdown on democracy supporters in the city gathers pace.
"Our work has to continue to remove the black sheep from the field of education," Chief Executive Carrie Lam told reporters.
"If there are a very tiny fraction of teachers who are using their teaching responsibilities to convey wrong messages to promote misunderstanding about the nation, to smear the country, and the Hong Kong government, without basis, then that becomes a very serious matter."
The Education Bureau said the primary school teacher, who was not named, had been struck off for "deliberately disseminating pro-independence messages".
"It can clearly be seen that Hong Kong independence is the theme of the lesson," deputy secretary Chan Siu Suk-fan told a press conference Tuesday afternoon.
Chan said the teacher's lesson plan and materials for Primary Five students -- who are about 10 years old -- involved discussion of a banned political party that advocated Hong Kong independence, and also touched upon topics related to Tibet, Xinjiang and Taiwan independence.
Education has become a key target for Hong Kong's pro-Beijing administration after months of huge and sometimes violent pro-democracy rallies last year.
Many young people took part in the protests, which called for police accountability and greater autonomy for the city.
China's central government imposed a sweeping security law on Hong Kong in June, outlawing public calls for independence and other allegedly subversive political views, with a maximum penalty of life imprisonment.
Education minister Kevin Yeung said he would not transfer the case to the national security bureau because the infraction occurred before the new law came into effect.
Amnesty International's Joshua Rosenzweig criticised the punishment and said it sent an "ominous message" to the city's educators on the risks of discussing current affairs, politics and human rights in the classroom.
"The Hong Kong authorities must not use national security as a pretext to unnecessarily censor educational activities, and they should not reprimand teachers for encouraging students to think about legitimate questions related to Hong Kong affairs," he said.