Hong Kong (AFP) - Hong Kong's human rights have "deteriorated severely" over the past year, with free speech under attack, Amnesty International said Tuesday, the latest report to criticise the city's government for restricting liberties.

The watchdog's year-end review cited a string of setbacks in freedoms, including the government's prosecution of leading democracy campaigners, its expulsion of a British journalist, the ban on a pro-independence party, and the barring of candidates from local elections.

Semi-autonomous Hong Kong enjoys freedoms unseen on the mainland, which are protected by the 50-year handover agreement between Britain and China, but fears are growing that those liberties are being eroded as Beijing flexes its muscles.

Amnesty accused the city's authorities of depriving citizens of their rights with increasing frequency in recent years by "expanding the interpretation of 'national security'".

"The concept of 'national security' as used by Hong Kong government... is arbitrarily applied to suppress dissent and political opposition," the report said, drawing comparisons to tactics favoured by repressive governments.

Last year Hong Kong authorities refused to renew a work visa for the Financial Times' Asia news editor Victor Mallet after he hosted a talk at the city's press club by pro-independence activist Andy Chan, whose party was later banned for reasons of "national security".

The decision to prosecute pro-democracy campaigners "threw a gloom over the right to peaceful assembly" in Hong Kong, the report said, warning that potential convictions could lead authorities to pursue more such charges in the future.

The review came days after the US State Department released a report warning that increased restrictions on Hong Kong's freedoms were hurting business confidence, and accused the city's government of sacrificing human rights to support mainland Chinese priorities.

The Hong Kong government hit back saying "foreign governments should not interfere in any form in the internal affairs" of the city.

In recent months, Hong Kong's government has barred several pro-democracy candidates from running for election and unveiled a draft law to punish anyone who disrespects the Chinese national anthem.