Executive councillor Ronny Tong said on Wednesday that the government's move to make calls for election boycotts illegal is "politically and ethically" the right thing to do and people should "stop making a fuss about it".
Tong said the SAR government is merely responding to Beijing's demand that election "sabotage" be outlawed.
While people will continue to be free not to vote if they don't want to, and it will remain perfectly legal to cast a blank or spoiled ballot, urging anyone else to carry out the same legal acts will be made illegal, with offenders liable to jail terms of up to three years.
The government has not explained how the casting of blank ballots could "manipulate" an election.
However, Tong said this would be a major issue when it comes to the chief executive vote – where just 1,500 people will select the territory's top local leader.
He noted that a candidate will need the endorsement of more than half of the election committee.
"The offence is essentially targeting incitement to cast an invalid vote publicly, which would cause severe repercussions, as opposed to individuals exercising their rights", Tong said on an RTHK programme, adding that the courts can act as safeguards against abuse of the future law.
When asked whether it would be illegal for any voters to say on social media how they cast their ballots, Tong, who is also a barrister, said people shouldn't "try to find legal loopholes".
Democratic Party chair Lo Kin-hei said on the same programme that he couldn't see the logic in banning appeals for blank votes, saying the more the authorities try to ban something, the more likely people will want to do it.
"Nowadays, when Hong Kong people see how the government does things – illogically and unreasonably – they'll just find their own ways to express themselves. Frankly speaking, people are not happy with the electoral changes," he said.