The foreign ministry office issued a statement expressing “resolute opposition” to the “erroneous” remarks and urged Tong to stop interfering in the internal affairs of Hong Kong and China.

“The ‘one country, two systems’ has been successfully implemented in Hong Kong and the [city’s] government has taken a series of measures to safeguard the constitutional order,” it said.

“The situation of Hong Kong is steadily heading in the right direction after the past year. There is no room for distortion and defamation.”

The Hong Kong Federation of Trade Unions (FTU) also released a statement “strongly condemning” the US diplomat for “interfering with Hong Kong’s affairs”.

“Kurt Tong’s remarks recently have harmed the US-China relations and the remarks were not beneficial for the exchanges between Hong Kong and the US,” the FTU said.

Differential treatment for Hong Kong will continue even though city is stuck in middle of US-China trade war, consul general Kurt Tong says

“In all of these cases and trends, the mainland central government appears to have been intimately involved in the Hong Kong government’s decision-making,” Tong said.

But Priscilla Leung Mei-fun, a member of the Basic Law Committee, which advises China’s National People’s Congress Standing Committee on Hong Kong’s mini-constitution, said Tong’s remarks showed that he did not have a good understanding of “one country, two systems”.

“Hong Kong is part of China and it’s not allowed to advocate Hong Kong independence,” she said. “The banning of the Hong Kong National Party is supported by the majority of Hong Kong people.”

Tong said that when he expressed his worries about the status of Hong Kong’s autonomy, he sometimes got resistance from those who believed that autonomy and freedom of expression did not matter in business.

“Neither the Chinese business community nor the foreign business community, they tell me, really cares about such cases. And as long as business decision-makers are happy, they say, Hong Kong’s economic future will remain bright,” the US diplomat said.

“I’m actually not so sure about that. I’m not confident that politics can be so neatly divorced from economics in how this city runs.”

Civic Party leader Alvin Yeung Ngok-kiu hit out at pro-Beijing politicians who condemned Tong, saying: “It’s a skill that is acquired, self-denial.”

Yeung added it was unlikely that Tong, as a professional diplomat who has been in Hong Kong for a long time, made the comments without consulting his higher-ups.

Jimmy Kwok Chun-wah, chairman of the Federation of Hong Kong Industries, said he was not aware of any foreign investors refused to invest in Hong Kong because of the political incidents Tong cited.

“On the contrary, the investors have been very actively asking how they can make use of the city’s strengths in tapping into the Greater Bay Area markets,” he said, referring to the plans to integrate Hong Kong, Macau and nine Guangdong cities into an economic powerhouse.

Tong made clear that a narrowing of the city’s political and democratic space is likely to harm Hong Kong’s market for ideas and innovation.

‘Bad’ US compound in Hong Kong to get facelift, says Consul General Kurt Tong

“But there are also other, more specific ways that the mainland central government’s desire to influence and control political conversations and events in Hong Kong could negatively impact the functioning of the economy, and the international business community’s role here,” Tong said.

He said it would “certainly impact the business environment” in Hong Kong if foreigners’ residency status were to become “broadly subject to political considerations”.

Lau Siu-kai, vice-chairman of The Chinese Association of Hong Kong and Macau Studies, a semi-official think tank, said Tong’s comments showed he did not understand the city’s constitutional duties.

“Hong Kong has the duties to safeguard national sovereignty under the ‘one country, two systems’ principle. A lot of foreigners do not understand that,” Lau said.

A spokesman from Hong Kong’s Constitutional and Mainland Affairs Bureau responded, saying: “Since the return to the Motherland, (the city) has been exercising ‘Hong Kong people administering Hong Kong’ and a high degree of autonomy in strict accordance with the Basic Law. The ‘one country, two systems’ principle has been fully and successfully implemented.”

Additional reporting by Sum Lok-kei