“Cross-boundary travel by land and air can only be allowed when the risks are acceptable and controlled measures are in place.”

Health secretary Sophia Chan Siu-chee, commerce minister Edward Yau Tang-wah and IT chief Alfred Sit Wing-hang will attend the press conference.

The government has been under tremendous pressure to reopen travel with other countries and neighbouring Guangdong province but the intermittent emergence of local Covid-19 cases with untraceable sources has stalled the negotiation process.

Hong Kong and Singapore last month reached an agreement to establish a travel bubble that would allow movement between the two places without the need for quarantine.

Yau earlier said the government would announce ticketing details in mid November and aimed to launch the bubble by the end of the month.

The formation of a travel bubble would be partially affected by the availability of a reliable rapid Covid-19 test. But the Post has learned the city would need to extend trials of the rapid RT-LAMP test at Hong Kong International Airport for one more week, after the results were less accurate than expected.

Last month, Chief Executive Carrie Lam Cheng Yuet-ngor also said the government was looking into arrangements to exempt Hongkongers living on the mainland from mandatory quarantine when they returned to the city.

Quotas would be set in the initial stage of the scheme.

Some 540,000 Hongkongers live in Guangdong.

Having allowed more travel, the health authorities were expected to plug loopholes that might allow the virus to spread, including a policy exempting more than 30 groups of people such as government officials, businessmen and truck drivers from mandatory quarantine when they travelled back from the mainland and were not subject to compulsory virus testing.

Two of the cases were locally transmitted, each with a traceable source. They included a teacher at SKH Holy Spirit Primary School in Sha Tin who lives in coronavirus-hit Tai Po district.

Three new infections were linked to an aircrew member from Kazakhstan who was earlier confirmed as infected, while the remaining four cases involved travellers from Indonesia, Ecuador and Germany, pushing the overall virus count to 5,389.

The latest fatality was an 88-year-old retiree who lived with his family in Kwai Chung. The death toll now stood at 108.

Professor David Hui Shu-cheong, a professor of respiratory medicine at Chinese University, said the three infections linked to the aircrew member exposed a loophole in the government’s rules.

Currently, locally based aircrew could head home or to a hotel directly for self-isolation after submitting a saliva sample for Covid-19 testing without the need to wait for the result. Similar arrangements also applied to foreign aircrew members who had a negative Covid-19 test result before arriving in Hong Kong.

“We should not allow aircrew members to wait at home for test results, as they could infect their family members while waiting,” he said.

Speaking before Tuesday’s Executive Council meeting, acting chief executive Matthew Cheung Kin-chung said the continuation of local cases of unknown origin remained a “worrying” threat.

He announced that social-distancing rules including mask-wearing and a ban on gatherings larger than four, would be extended until at least November 19.

“If there is a resurgence of cases and another large-scale community outbreak, the government will have no choice but to tighten anti-epidemic measures to safeguard the public health,” he said.

Additional reporting by Natalie Wong