Former tourism commissioner Mike Rowse on Friday warned that the SAR's tourism sector will likely need two years to recover to pre-pandemic levels, despite a boost from a major government promotion campaign that will see half a million free air tickets handed out.

Speaking on RTHK's Hong Kong Today programme, Rowse said the administration's "Hello Hong Kong" initiative, announced on Thursday, was a good start, but a full recovery wouldn't be possible in the short term after three years of travel restrictions amid Covid-19.

"It's far too big a task," Rowse told RTHK's Vicky Wong. "It's going to take a long time to get those sorts of numbers.

"Just getting the flights back, as we know, is going to take months and months. Getting the aircraft back in service, getting the crews back, re-establishing the routes that we had, that's going to take a long time.

"These things are desirable, but we're not going to get back to anything like the numbers in 2023; hopefully 24/25."

He said key sectors such as the cruise and exhibition sectors typically operated on three-year planning cycles, meaning Hong Kong had missed out in the past few years and may have to wait to get back onto schedules.

However Rowse, who also previously led the investment body InvestHK, said the SAR still had a lot to offer visitors, and the industry would be pleased to see the government making serious efforts to attract tourists.

Officials said on Thursday that they hoped to lure tourists with at least one million vouchers, worth more than HK$100 each, to use on drinks, food, shopping or transport. But Rowse said the free air journeys would be a major attraction.

"I'm sure people will welcome this and people everywhere will be looking for chances to take advantage of it, so it's going to generate excitement, and that's a good thing," he said.

"Get one person and he's not going to come by himself, he's going to come with a couple of friends or family members and the message will spread. Let's make sure the message is right."