Japanese Prime Minister Fumio Kishida said Thursday that "maximum caution" is warranted as medical experts warn of an "explosive" surge in COVID-19 cases in Japan, but no new restrictions on people's movements are planned for now.

Speaking at a press conference, Kishida said the government will accelerate the vaccination drive, with about 8 million health care and nursing care workers targeted for fourth shots.

Japan has seen the number of newly confirmed coronavirus cases surging in recent days ahead of an extended weekend from this Saturday and a summer holiday season.

"Coronavirus infections are spreading nationwide and the number is increasing in all age brackets, especially among young people," Kishida said, raising concern about the highly transmissible BA.5 strain becoming dominant.

Japanese Prime Minister Fumio Kishida attends a press conference in Tokyo on July 14, 2022. (Kyodo) ==Kyodo

Still, he stressed the need to keep the economy going while taking precautionary steps against COVID-19 at the same time.

"We will first use our strengthened (COVID-19) response capability fully and we are not thinking about imposing new restrictions on people's behavior at this point," the prime minister said.

The resurgence comes as Japan has been relaxing its border controls that were criticized at home and abroad for being too stringent. Japan still maintains a daily entry cap but has started accepting foreign tourists on package tours.

Kishida said the government will weigh various factors such as demand, the infection situations at home and abroad, and border control measures taken by other nations in deciding whether to take further easing steps.

"We are not considering strengthening border control steps now but we will continue to monitor developments carefully," he said.

During the press conference, Kishida said the government will continue to try mitigating the blow from accelerating inflation in Japan, largely driven by higher energy, raw material and food prices, adding that the government is not hesitant about using fiscal spending for the purpose.

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Energy security has become another key issue for resource-poor Japan, which relies heavily on foreign energy resources. Major developed economies are curbing dependence on Russian fossil fuels while crude oil and other energy prices have been surging.

"There is no single perfect energy source for resource-scarce Japan," Kishida said, calling for maximum use of nuclear energy to create the "balanced" mix of multiple energy sources.

Safety concerns remain strong among the Japanese public about the use of nuclear power following the 2011 Fukushima disaster caused by a massive earthquake and tsunami.

Kishida revealed plans to ensure up to nine nuclear reactors will be operational this winter to cover around 10 percent of total energy consumption in Japan.

Of 10 reactors allowed to operate after meeting the nuclear regulator's safety and anti-terrorism requirements, five are currently in operation, although one of them is due to be halted in September to implement an additional measure against possible terror attacks. The remaining five are offline due to maintenance work or terrorism countermeasures being implemented.

On top of that, the government will boost the supply of thermal power by using an additional 10 units to meet peak demand, Kishida said.