However, Sun Island English Kindergarten was quick to point out that the activity sheet had been in use for more than a decade, and was first used to commemorate “people who help us” to mark the 60th anniversary of the city’s Police Dog Unit.

“We have received emails and comments with complaints and accusations following teaching materials posted on social-media platforms,” it said in a statement.

“School management and teachers have always followed professional conduct and principles to help pupils develop the correct values, as well as tolerance and respect for others’ opinions. We would not bring politics onto our campuses.”

The row started after the worksheet was posted on social media on Tuesday, and attracted a wave of criticism and suggestions its use was politically motivated.

Images online also showed a comparison between the worksheet, which placed the policeman and the dog side by side, and a similar worksheet that placed a rabbit beside a dog, both asking students to colour the picture that matched the listed word.

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Some online users claimed the rabbit version was used last year, and the policeman and the dog this year.

But Sun Island said the two worksheets were given to different classes in February, with three-year-old (K1) pupils asked to colour in the officer and the dog, while the other version was for pre-nursery children. In its statement the kindergarten said the different designs were based on learning progress.

The Education Bureau said it had not received any complaints about the matter, but would contact the kindergarten to learn more.

“It is understandable that parents and members of the public have become more concerned about schools’ teaching materials,” Wong said. “Schools should be more careful on whether any of these materials could trigger unnecessary speculations or suspicions.”

But Ip Kin-yuen, education sector lawmaker and vice-president of the pro-democracy Professional Teachers’ Union, believed the worksheet itself was not a problem and people had jumped to the wrong conclusion.

“The troubles were not [caused] because of the worksheet itself, but because of the perception of some members of the public … which have brought more complications to the education sector,” he said.

Teaching material in schools has come under increasing public scrutiny amid heightened political tension.

The Education Bureau, which slammed the content for being “obviously untrue”, said it would look into the incident, including whether the teacher was involved in any acts of professional misconduct.