• Tighter restrictions — including the closure of bars, cinemas and fitness centers — kicked in on Friday last week and are set to last until Jan. 20.
• There will likely be more opposition to Hong Kong's "draconian measures" given that the variant appears to be less dangerous, said Kurt Tong, previously U.S. consul general and chief of mission in Hong Kong and Macao.
• The government is "fully committed" to zero Covid, and "really can't back away from that approach, regardless of the economic impact, without some instruction from Beijing to do so, which I don't see coming," he said.

The highly transmissible omicron variant is going to be a "very difficult challenge" for Hong Kong as the city sticks to its zero-Covid policy, a former U.S. diplomat told CNBC.

There will likely be more opposition to "draconian measures" given that the variant appears to be less dangerous, said Kurt Tong, who was previously U.S. consul general and chief of mission in Hong Kong and Macao from August 2016 to July 2019.

Tighter restrictions — including the closure of bars, cinemas and fitness centers — kicked in on Friday last week and are set to last until Jan. 20.

"We are facing a very dire situation of a major community outbreak any time, and that's why we have to take very decisive measures," Chief Executive Carrie Lam said when announcing the new rules.

It will be very difficult to achieve zero Covid given the transmissibility of the omicron variant, and "there will be more political pressure to not have draconian measures be instituted against a relatively small risk for most of the vaccinated population," said Tong, who is now partner at business advisory firm The Asia Group.

Around 70% of Hong Kong's population has received two doses of a Covid vaccine, according to government data. However, a "significant proportion" of elderly people are unvaccinated, Tong told CNBC's "Squawk Box Asia" on Thursday.

The government is "fully committed" to zero Covid, and "really can't back away from that approach, regardless of the economic impact, without some instruction from Beijing to do so — which I don't see coming," he added.

Unhappy but resigned

Asked about the public and business sentiment toward zero-Covid strategy, Tong said "unhappiness is the primary feeling — but also a sense of resignation."

People understand that Hong Kong wants to reopen the border with mainland China, and that it needs to follow the same zero-Covid policy in order to achieve that, Tong said.

"That's just the way it's going to be," he said.

Tong added that he doesn't expect the border with China to open in the first half of this year.

"The omicron challenge is just very significant, and so everyone's going to be quite conservative in their decision making," he said.

Allan Zeman, chairman of property developer Lan Kwai Fong Group, previously defended Hong Kong's strict rules.

"I think in general, we are safe and it's different to the horror stories I watch in Europe and the United States at the moment," he said in December. Zeman was a candidate in last year's Legislative Council elections but did not manage to win a seat.

Hong Kong has reported 12,821 confirmed Covid cases and 213 deaths since the pandemic began.