Hong Kong and Singapore put their planned travel bubble on hold.

The governments of Hong Kong and Singapore have temporarily scrapped a plan for a travel bubble, as Hong Kong grapples with a spike in coronavirus infections. The delay underscores the challenges of reopening international travel routes as efforts to control the virus remain unstable across the world.

The arrangement between the two Asian financial centers, which would allow travelers to bypass quarantine, was set to begin on Sunday. But Edward Yau, Hong Kong’s secretary of commerce, said on Saturday that the two cities were pushing back the plan for two weeks because of a “recent upsurge in local cases” in Hong Kong.

“For any scheme to be successful, it must fulfill the condition of securing public health and also making sure that both sides would be comfortable and feel safe about the scheme,” Mr. Yau said, describing the delay as a “responsible” decision. Further announcements about the plan will be made by early December, he added.

The travel bubble between Hong Kong and Singapore would have allowed one designated daily flight into each city, carrying up to 200 passengers who tested negative for the virus.

After a period of relatively few infections, Hong Kong recorded 43 new cases and was verifying more possible ones on Saturday, the city’s health authorities said, up from 26 new cases on Friday. Singapore on Saturday recorded five infections, and said that all of them had been brought in from abroad.

Hong Kong has also further tightened its social distancing rules, banning live performances and dancing at bars and nightclubs, and banning room rentals for private parties.

In other news from around the world:

• Two of China’s largest port cities, Shanghai and Tianjin, are conducting major testing efforts after announcing a handful of locally transmitted coronavirus infections, renewing worries about whether the country can continue to keep out the virus after coming close to eradicating it over the summer. Tianjin said on Friday that it had discovered four cases, all in its port area, and it sealed off the residential community there. Shanghai said on Saturday that an airport cargo security officer and his wife, a nurse, had both been infected.

• A day after Japan reported a record 2,427 new cases, Prime Minister Yoshihide Suga said on Saturday that the country would scale back a subsidy program for domestic tourism in places where infection rates are high. The roughly $16 billion “Go to Travel” program was meant to stimulate the economy, but many questioned its wisdom. Mr. Suga told the Japanese parliament on Friday that about 40 million trips had been taken through the program so far, and that 176 of the tourists had contracted the virus. Toshio Nakagawa, the head of the Japan Medical Association, has said that while there is no concrete evidence linking the program to the country’s recent surge in infections, “there is no mistaking that it acted as a catalyst.”

• Portugal’s prime minister, Antonio Costa, said on Saturday that domestic travel would be banned and schools closed around two upcoming holidays in a bid to reduce the spread of the coronavirus ahead of Christmas, Reuters reported. Travel between municipalities will be banned from 11 p.m. on Nov. 27 to 5 a.m. on Dec. 2, and then again from 11 p.m. on Dec. 4 to 5 a.m. on Dec. 9, to prevent movement around national holidays on Dec. 1 and Dec. 8. Schools will close on the Mondays before both holidays, and businesses must close early.