The government is planning to add three prefectures neighboring Tokyo, as well as the western prefecture of Osaka, to areas under the COVID-19 state of emergency following a recent surge in the number of coronavirus cases, a government source said Thursday.

The state of emergency in Osaka as well as Saitama, Chiba and Kanagawa prefectures will be effective from Monday through Aug. 31, bringing the total number of prefectures under the emergency to six, including Tokyo and Okinawa, at a time when the capital is hosting the Olympics.

The state of emergency in Tokyo and the southern island prefecture, which was due to end on Aug. 22, will be extended to Aug. 31, the source said.

The governors of Saitama, Chiba and Kanagawa jointly requested that the central government add their prefectures to the areas covered by the emergency.

Earlier in the day, Chiba Gov. Toshihito Kumagai said at a press conference that he has "a strong sense of crisis" over the rapid spread of the virus.

Prime Minister Yoshihide Suga told reporters the government will consult with experts Friday on the planned expansion of the virus emergency.

Japan's daily total of COVID-19 cases topped 10,000 for the first time on Thursday, hitting the highest-ever level for the second straight day. Tokyo, under the emergency since July 12, confirmed 3,865 cases, with Kanagawa reporting 1,164. Both figures were record single-day highs.

The three prefectures neighboring Tokyo are currently under a quasi-state of emergency, which carries fewer restrictions on business activities than a state of emergency.

Shigeru Omi, Japan's top coronavirus adviser, urged the government in a parliamentary hearing Thursday to send out a strong message to people as he warned about the increased strain on the health care system.

"I have a strong sense of crisis. There are not many factors that will lower the current level of infections," said Omi, an infectious disease expert who heads the government subcommittee on the coronavirus.

He said the "greatest danger is in the fact that the general public does not share a sense of crisis," and that such a situation would lead to further spread of the virus.

"I want the government to send out a message that is clearer and stronger than ever without missing this timing," Omi said.

The surge in infections comes amid the spread of the highly contagious Delta variant of the coronavirus first detected in India.

While the number of people going out has decreased compared with the period before the state of emergency was declared, the pace of decline is not sufficient with Tokyo hosting the Olympics, according to experts.