The Chinese embassy in Ottawa has urged Canada not to interfere in Hong Kong affairs after Canadian Foreign Minister Melanie Joly said the city's freedom was being suppressed.

In a statement on Friday, the 25th anniversary of Hong Kong's return to Chinese rule, the embassy said external forces should not make "irresponsible remarks".

"The so-called deep ties between Canada and Hong Kong cannot be a reason for Canada to interfere in Hong Kong affairs," it said.

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"The Canadian side's smearing of the successful application of 'one country, two systems' is futile, and it is impossible to intervene in Hong Kong affairs."

The embassy said the efforts "will not shake China's firm determination to fully and accurately implement one country, two systems and China's safeguarding of national sovereignty."

On Thursday, Joly said Canada had direct ties with Hong Kong, with an estimated 300,000 Canadians living in the city and more than 100 Canadian companies with a presence there.

She also Hong Kong was the site of the first land battle Canadians fought in the second world war.

But she said freedom of speech and peaceful expression of alternative views had been suppressed over the past two years with the imposition of a national security law in Hong Kong.

"Media freedoms continue to be eroded, following the closure of Apple Daily, Stand News and other independent media outlets," it said.

"Canada urges the People's Republic of China and Hong Kong authorities to adhere fully to the one country, two systems framework set out in Hong Kong's Basic Law, which also took effect 25 years ago."

She said the high degree of autonomy provided under the Basic Law and China's commitment to respect the rule of law and to uphold human rights was essential "for the stability and prosperity of Hong Kong as they were when committed to in 1997".

The United States, Britain and Australia all released statements saying they were concerned about Hong Kong's autonomy.

Australian Foreign Minister Penny Wong said Australia remained deeply concerned by the continuing erosion of Hong Kong's rights, freedoms and autonomy since the imposition of the national security law.

British Prime Minister Boris Johnson said Britain would not give up on Hong Kong and would do all it could to hold Beijing to its commitments, while US Secretary of State Antony Blinken said Hong Kong and Beijing authorities no longer viewed democratic participation, fundamental freedoms and an independent media as part of promised autonomy for the city.