The policy chief of Japan's ruling Liberal Democratic Party on Monday called for active debate in the Diet on legal revisions that would introduce lockdowns to contain the spread of the novel coronavirus.

"We need to make preparations. It's not that we will immediately discuss this in the Diet, but we need to consider legal revisions as needed from the standpoint of the people," Hakubun Shimomura told reporters.

His remarks came a day after the National Governors' Association agreed to ask the central government to study ways to impose lockdowns to better contain the virus in Japan amid growing concern about the transmission of the more contagious Delta variant.

People wearing masks walk in Tokyo's Shibuya area on July 31, 2021, amid the coronavirus pandemic. (Kyodo)

Prime Minister Yoshihide Suga, however, has appeared reluctant to introduce such a measure, saying he believes legislation that would enable the government to impose the kind of hard lockdowns seen in many major cities abroad last year would "not suit" Japan as they have not prevented the virus from spreading overseas.

Chief Cabinet Secretary Katsunobu Kato said at a regular news conference on Monday that Japan cannot impose a lockdown under the current system, noting it would be "a major restriction of individual rights."

A Japanese law covering measures against the novel coronavirus states that restrictions on individual rights must be kept to a minimum, given that the Constitution calls for the respect of basic human rights.