A mainland source said a successful dry run earlier this month along with a stepping up of both manpower and technical capabilities meant that expanding the previously proposed quota was a real possibility.

“I would say that, given our preparations and testing, catering for a daily limit up to 3,000 as a start is doable, without any compromise in pandemic-control standards,” he said. “But the final numbers need to be confirmed at a later date.”

But he also said the current outbreak in Guangdong – to which travel will initially be restricted – remained a concern for the launch of the border reopening.

“Things are very fluid now. While the outbreak is under control so far, and we know Guangdong is doing its best to trace close contacts and lock down towns with confirmed cases, no one can be 100 per cent sure of what’s coming our way,” he said.

“We have to do our best and always prepare for the worst.”

Could Guangdong Covid-19 cases scupper Hong Kong-mainland border reopening?

Four more cases were reported in Dongguan on Wednesday, taking the number of infections detected since Tuesday to eight.

Dongguan’s Dalang town has been included in a list of places where Hong Kong’s quarantine-free “Return2HK” and “Come2HK” schemes were not applicable.

Guangzhou, which saw its first Omicron case on Tuesday, also reported one more Covid-19 infection involving an airport worker who was handling transit passengers. It was not yet known whether that case involved the Omicron variant.

Danny Lau Tat-pong, honorary chairman of the Hong Kong Small and Medium Enterprises Association, said his own sources had confirmed the daily quota for cross-border travel would be 3,000.

Every chamber of commerce would be granted a quota based on the size of the organisation to be divided among its members, Lau said.

“Businessmen who were [previously] exempted from compulsory quarantine arrangements in Hong Kong will be given priority,” he told a radio programme.

“I think it is more appropriate to let the chambers make the decision, as it is better than waiting for the government to make the approvals, especially when they are not insiders in our industries.”

He added that distributing the passes on a first-come, first-served basis was not a good idea given that business owners more adept with technology might scoop up the available spots.

The mainland source, meanwhile, added that the suspension mechanism for the quarantine-free scheme was likely to be triggered if an involved city were to be considered “medium risk”, currently defined by the State Council as having no more than 10 local cases within 14 days.

Areas with more than 10 cases in two weeks are defined as “high risk”.

But the final decision for each suspension would be made by the National Health Commission, the source said.

“The National Health Commission will oversee the process and work with local health commissions to decide on risk levels and whether it is necessary to suspend the [travel] arrangement,” he said.

Respiratory medicine expert Dr Leung Chi-chiu said the epidemic situation in Guangdong, especially in Dongguan, might not hinder the broader plans to reopen the border.

“If there is only an outbreak within a district, the border reopening arrangement is unlikely to be affected,” Leung said.

He said the Covid-19 cases identified in Dongguan so far had been among patients’ close contacts or the targeted population, meaning they were all traceable. The risk would only be elevated if untraceable infections were identified, he added.

Fewer than 10 people tested preliminary-positive for Covid-19 on Thursday, including the Cathay pilot, who had returned from Anchorage, Alaska on December 13 after flying out of the city two days earlier. The pilot tested negative upon arriving back in Hong Kong.

Local cargo pilots who fly from Anchorage have a blanket exemption from quarantine, while passenger flight crew need to quarantine for seven days upon returning to the city.

Exempted cargo crew, however, are subject to daily testing as part of beefed-up measures introduced in response to cases involving three subsequently sacked Cathay pilots who returned to Hong Kong with Covid-19, having left their overseas hotel room in contravention of company policy and government instructions.

BioNTech booster shots available to all in Hong Kong from January

Meanwhile, Hong Kong confirmed 10 new Covid-19 cases, all imported. Among them were four arrivals on flight RA409 from Nepal, triggering a 14-day ban on Nepal Airlines. The national carrier will not be able to fly from Kathmandu to Hong Kong again until December 29.

Another of the confirmed cases was a crew member of the cargo ship Glory Sky, the fourth to test positive from the vessel since it arrived in the city from Japan.

Hong Kong’s official tally of infections now stands at 12,506, with 213 related deaths.

Separately, health authorities will ban visitors from three more countries to shut out Omicron cases, adding Kenya, Lithuania and Rwanda to the city’s high-risk Group A list, with the move to take effect on Sunday.

Under the rules, non-residents cannot enter Hong Kong from Group A countries while city dwellers, who must be fully vaccinated, face a mandatory 21-day quarantine.

Ninety places are now classified as Group A, 65 of which were added since the World Health Organization designated Omicron as a variant of concern on November 26.