Passengers arrive at Hong Kong International Airport. File

The other countries are Australia, Canada, France and Philippines.

Flights to Hong Kong are down 90% and hardly any are allowed to transit as the financial hub isolates itself from the world in the hope it can contain a coronavirus outbreak, even though new infections are overwhelmingly local transmissions.

China will fully support Hong Kong with its "dynamic zero" coronavirus strategy as the territory battles an escalating outbreak, its office overseeing matters in the city said.

The central government was "highly concerned" about the safety and health of residents as well as the economy and people's livelihoods, a spokesperson for the Hong Kong and Macau Affairs Office (HKMAO), which comes under China's State Council or cabinet, said in a statement.

It said it would hold a meeting of mainland and Hong Kong officials in neighbouring Shenzhen "in the near future" to "maintain stability" and come up with policies to support Hong Kong's fight against the disease.

"As long as Hong Kong asks, the motherland will surely respond ... Hand in hand, we will surely be able to overcome the epidemic soon," it said.

The Chinese government will help improve Hong Kong's testing capability and set up another quarantine facility, the South China Morning Post reported, citing a Beijing-based source.

The mainland is also preparing to send thousands of medical and lab workers and millions of testing kits to Hong Kong, with the daily coronavirus screening capacity to be increased from 100,000 tests to 3000,000 tests.

The global financial hub has seen a 10-fold rise in cases since Feb. 1 and medical experts warn the city could see 28,000 daily infections by the end of March, with the unvaccinated elderly a particular worry.

The increase is proving to be the biggest test for Hong Kong's policy of virus suppression as capacity for hospital beds, isolation and coronavirus testing nears its maximum.

Reuters