HONG KONG — Hong Kong’s government says the start of a proposed quarantine-free travel bubble with Singapore has been postponed following a spike in untraceable cases in the Southeast Asian city state.

A news release Monday said the two governments had decided to defer the start of the air travel bubble originally slated for May 26 “in view of the recent COVID-19 epidemic situation in Singapore.”

It said both governments remained committed to the bubble and would continue to closely monitor developments in both places, with an emphasis on the effectiveness of the stepped-up anti-epidemic measures that took effect in Singapore from Sunday and are due to run through June 13. A further announcement would be made on or around that date with a view to “resuming air travel between the two … in a gradual and orderly manner under a set of stringent public health protocols,” the notice said.

The announcement came after Singapore restricted gatherings to just two people and limited restaurants to delivery or takeout service only.

The number of new cases has risen to 71 in the past week, from 48 the week before, as infections rise from a cluster tied to Changi Airport. Infections not linked to identified cases have risen to 15 in the last week, more than double the week before.

The health ministry said the pattern of infections not connected to known cases suggested the virus was spreading and current measures were insufficient to stop it.