When CNBC asked whether the scheme is on track to begin on May 26, Dr Balakrishnan said: “As of now the plan is yes, but we have to watch how the situation evolves over the next few days.”

The launch of the 'air travel bubble' — initially slated for November 2020 — had been postponed multiple times after a flareup in coronavirus infections in Hong Kong.

The two cities said last month that the scheme will start with one flight a day into each city, with up to 200 travelers on each flight.