People wearing face masks walk in Osaka's Kita Ward on Jan. 9, 2021, amid the coronavirus pandemic. (Kyodo) 

Four people who arrived at Tokyo's Haneda airport from Brazil have been found to be infected with a new variant of the novel coronavirus, officials said Sunday, amid a resurgence of infections in Japan.

The confirmation came as Prime Minister Yoshihide Suga said the same day that the government will take "a few days" before judging whether to expand a state of emergency declared over the coronavirus pandemic to Osaka, Kyoto and Hyogo prefectures.

The National Institute of Infectious Diseases said there was no evidence at present that the new variant was more transmissible or likelier to cause serious symptoms.

Takaji Wakita, head of the institute, said the variant showed some similarities to those spreading in Britain and South Africa.

Concern over the new, potentially more infectious coronavirus variants discovered in the two countries prompted the government to halt the entry into Japan of nonresident foreign nationals.

The ministry said the four passengers arrived at Haneda airport on Jan. 2 from Amazonas, Brazil. They tested positive after airport quarantine.

Of the four, a man in his 40s had been hospitalized due to difficulty breathing, a woman in her 30s had complained of throat pain and headaches, and a male teenager had developed a fever. A female teenager had shown no symptoms.

Earlier in the day, Suga told a program on public broadcaster NHK, "I was told that we need to watch the situation for a few days, so I am thinking that way," referring to the opinion of a government panel of experts that monitors infection trends.

He was speaking a day after the governors of the three western prefectures asked the central government to extend the state of emergency, which took effect Friday for the Tokyo region, to their areas in response to a resurgence in coronavirus infections.

The government has requested the implementation of measures such as the shortening of restaurant opening hours and the promotion of teleworking across the three prefectures.

"I know they are in a tense situation. We are ready to respond immediately if necessary," Suga added.

By declaring a state of emergency, the central government enables local authorities to urge people to stay at home as much as possible and to call on eateries to shorten opening hours.

In April, Japan declared a state of emergency for some of the country's 47 prefectures and later extended it nationwide. The government fully lifted it in late May.

The resurgence of infections has been increasing the strain on the country's medical system.

Opposition parties have criticized Suga for being slow to declare the one-month state of emergency covering Tokyo and the neighboring prefectures of Chiba, Kanagawa and Saitama.

The decision finally came after the governors of the four local governments requested it earlier this month.

A record-high 852 people had serious COVID-19 symptoms, the ministry said.

Over 6,000 daily coronavirus infections were reported nationwide, after topping 7,000 on Saturday for the third day in a row.

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