Chief Cabinet Secretary Suga Yoshihide says the Japanese government continues to watch the situation in Hong Kong with grave concern.

Suga spoke to reporters on Tuesday after Hong Kong police arrested pro-democracy activists and a media tycoon under the territory's new national security law.

The Japanese tradition of visiting ancestral graves during the Bon summer holidays has been largely disrupted by the new coronavirus outbreak. Some families are asking a local cemetery headstone maker in the western prefecture of Tottori to send its staff to their family graves.

On Monday, a staff member was seen cleaning and polishing the headstone of a family grave on behalf of a woman who lives in Aichi Prefecture, central Japan.