Japan reported over 1,000 new daily coronavirus cases Thursday for the first time since Aug. 21, as the government has eased restrictions and promoted travel within the country to help support the economy hit hard by the pandemic, according to a Kyodo News tally based on official data.

The number of additional infections in various parts of Japan has been trending upward in recent days, with some health experts warning that colder temperatures, forcing people into often poorly ventilated indoor environments, are believed to make the virus more transmissible.

In addition to Tokyo and Osaka, 119 new cases were reported in Hokkaido, a popular tourist destination, its highest single-day increase. It is the first time that the country's northern main island has seen a daily figure above 100 since the outbreak of the virus.

Some clusters of infections were reported in Susukino, a major nightlife entertainment district in Hokkaido.

Atsuo Hamada, a professor at Tokyo Medical University, attributed the increase in cases in Hokkaido and the Tohoku region in northeastern Japan, possibly to the cold weather, which is also believed to be likely behind the surge in patients in Europe.

"We need to be vigilant," he said.

Tokyo confirmed 269 new infections, bringing its cumulative total to 31,893, the highest by far among Japan's 47 prefectures. The new tally follows 7,354 virus tests conducted on Monday, the highest single-day figure for the Japanese capital so far.

Of the 269, 154 contracted the virus via unknown routes, the metropolitan government said.

Osaka Prefecture, which has the second-highest cumulative total, confirmed an additional 125 cases. The daily increase in the western Japan prefecture has often surpassed 100 since late October compared with earlier in that month when the figure stayed around 50.

"While I cannot say whether this is a third wave (of the coronavirus), it is true that there is a rise" in the number of cases, Osaka Gov. Hirofumi Yoshimura said, adding he will hold a conference with a panel of experts possibly next week.

Japan on Thursday confirmed an additional 1,050 cases, bringing the nationwide tally to 105,688 cases, including around 700 from the Diamond Princess, a cruise ship that was quarantined in Yokohama in February. The death toll now stands at 1,821.

"Effectively the third wave has arrived," Aichi Gov. Hideaki Omura said, referring to the increase in infections in his prefecture over the past week.