"We are finalizing the details of our revised agreement and hope to announce our plans soon," he said in a statement issued by Singapore's Ministry of Transport.

This comes after Hong Kong Chief Executive Carrie Lam said on Tuesday that the territory plans to allow only residents who have been fully vaccinated against the coronavirus disease to travel to Singapore under the travel bubble, describing this requirement as the "basis for discussion" between the two cities.

This is despite authorities in Singapore not requiring mandatory vaccinations for Hong Kong travellers under the arrangement, she noted.

“We want to provide incentives to encourage Hong Kong citizens to get vaccinated," Lam said.

Ong had last month said that Singapore was studying a proposal from Hong Kong to reopen borders safely, after the territory had managed to bring the pandemic under control.

The air travel bubble between Hong Kong and Singapore was originally scheduled to begin in November last year, but was deferred due to a spike in infections in Hong Kong.

The scheme would have allowed people to travel between the two cities with no restrictions on the purpose of travel and no requirement for a controlled itinerary or sponsorship.

Travellers would be subject only to coronavirus disease tests, without the need for quarantine or stay-home notices.