More than 40 percent of a top US business group's members in Hong Kong said they plan to leave the city in a survey released Wednesday, highlighting growing concerns over Beijing's sweeping national security law.

China blanketed Hong Kong in a broad security law last year to snuff out dissent after months of huge and often violent democracy protests.

The American Chamber of Commerce survey -- conducted between May 5 and 9 -- found 42 percent of 325 respondents said they were planning a move away, with a significant majority (62 percent) citing the national security law as a key reason.

Other reasons given included the city's pandemic control measures, its future competitiveness, the high cost of living and concerns over the quality of education as dissent is quashed.

"While people share their love for living in this dynamic city, they also reveal growing underlying tensions and nagging fears," said Tara Joseph, AmCham's president.

The American Chamber of Commerce survey -- conducted between May 5 and 9 -- found 42 percent of 325 respondents said they were planning a move away
The American Chamber of Commerce survey -- conducted between May 5 and 9 -- found 42 percent of 325 respondents said they were planning a move away AFP / Anthony WALLACE

"Previously, I never had a worry about what I said or wrote when I was in Hong Kong," one respondent wrote in comments published in the survey.

Another cited an "increase in anti-foreigner sentiment in the media and government statements".

Of those who are planning to move, three percent said they intended to leave immediately, 10 percent said by the end of summer, 15 percent by the end of the year, and 48 percent said they would leave within three to five years' time.

"AmCham strongly suggests that the government pay close heed to the sentiment of expatriates in Hong Kong and work towards allaying major concerns through stronger understanding of Hong Kong's international talent, lest the city lose competitiveness versus other business hubs," AmCham said.

Hong Kong authorities say the security law was needed to return stability after 2019's protests
Hong Kong authorities say the security law was needed to return stability after 2019's protests AFP / DALE DE LA REY

Commerce Secretary Edward Yau dismissed the survey results saying he believed most international businesses backed the security law and wanted to stay.

"We have seen stability brought back, they are grateful," he told reporters, adding the government's own surveys showed no uptick in plans to leave by international companies.

US businesses have previously raised fears they may be vulnerable to geopolitical tensions as relations between Washington and Beijing plummet.

A similar AmCham survey last August showed that 39 percent of 154 firms it surveyed had plans to move capital, assets or operations out of the city due to the national security law.

But moving is a costly exercise and there have been few signs major American multinationals are about to pull out en masse.

Detractors say its deliberately broad wording and application has criminalised much dissent.

The vast majority of the more than 100 people arrested so far have been detained for their political views. Bail is usually denied to those arrested and those convicted face up to life in prison.

On Tuesday, Hong Kong's police chief Chris Tang warned that publishing "fake news" could amount to a breach of the national security law.

"As long as you broke the law, we will find evidence to prove that you committed a crime. You can only wait at home for us to arrest you. But you don't have to worry at all if you didn't break the law," he said.