Justice minister Paul Lam said on Sunday that national security convictions have been based on remarks that were very specific. He made the comments on Commercial Radio, while discussing the law's implementation nearly three years since its introduction.

"What we're talking about in the convicted cases is that, you are inciting others to commit secession or subvert the state," he said.

"This involves a very specific style of comment - that you have to mess with your own country, such as by pursuing Hong Kong independence or damaging our country's constitutional order."

Lam said with fewer than 30 people convicted since the legislation was introduced nearly three years ago, everyone would agree that the law affects only an extremely small number of people, when compared to the local population of seven million.

On suggestions that people's freedoms had been affected, the minister said the public should look at security law convictions and notice that what's been outlawed includes extreme acts such as an activist ramming his motorbike into a row of policemen while displaying a seditious flag.

The secretary also took aim at overseas countries critical of the security law, particularly the US.

He accused them of launching the attacks for geopolitical reasons, as part of plans to contain China.

"From time to time we get a new report on Hong Kong, there's nothing new. They just keep repeating the same allegations, but they didn't offer specific, objective examples to support their arguments. The so-called facts they cited, we have rejected countless times in our explanations," he said.

The minister said he had personally become bored of the comments, but noted that officials would continue to rebut any attacks.