Lee Man-ho and the highly offensive notice displayed in his office.

A sign by Sham Shui Po District Council member Lee Man-ho barring pro-establishment "blue camp" supporters and dogs from his office is disgraceful.

The notice - which reads, "No blue fans and dogs allowed" - has been on display at Lee's office since January.

But it failed to draw much public attention until a photograph of it went viral on social media recently and stoked anger among not only government supporters, but also some among the "yellow" opposition who also disagreed with the outrageous slogan.

In one of Bruce Lee's kung fu movies, there was a scene shot in Shanghai's Huangpu Park with a sign saying, "No dogs and Chinese allowed."

Although the sign featured in the film was fictitious, some historians said it dramatized the inequality between Chinese and foreigners in the mainland during the 1890-1928 period.

When the Sham Shui Po councillor was confronted by the media for clarification, he wrongfully insisted that it was absolutely fine to segregate his constituents.

He argued that he was relentlessly critical of the government and its blue camp during the election campaign and his "yellow" supporters voted for him because of this.

Lee was not the only one to see nothing wrong in differentiating constituents according to their political colors - but his action in putting up the hugely offensive notice must have touched many raw nerves given the recent media publicity he has received and the death threats made against him.

The district council election is long over and the winners are morally bound to treat every constituent equally.

In response to media enquiries, the Equal Opportunities Commission commented that - although it disagreed with Lee's notice telling "blue" supporters and dogs to go away - it was powerless to act.

That is because the notice apparently did not contravene any anti-discrimination laws which are confined to dealing with discrimination in relation to gender, pregnancy, marital status, disability, family and ethnic origin.

The EOC's answer was disappointing. Although it may be correct in the strictest interpretation of existing legislation, surely the notice displayed by Lee is an expression of hatred.

Putting up a sign that equates people with dogs is no less offensive than government supporters calling "yellow" camp followers "cockcroaches."

It is more likely than not that the ongoing trend of community polarization will continue despite the outbreak of the novel coronavirus that many hoped would help lower political hostilities in Hong Kong.

As society continues to divide, supporters of rival camps will undoubtedly keep trading insults with each other.

I wonder if it is time to follow the practice of some western democracies to review our anti-discrimination laws to outlaw hate speech and make it unacceptable to call somebody a dog or a cockcroach.

Such derogatory comparisons are totally unsuitable in a civilized world. Stop these hateful dogs and cockcroaches linguistics.