Japan's death toll from the novel coronavirus topped 1,000 on Monday, with those in their 60s and above making up over 90 percent of the fatalities.

The tally includes 13 deaths among infected passengers of the Diamond Princess cruise ship that was quarantined in Yokohama in February. The first death in Japan was recorded on Feb. 13.

The country's death toll has been on a downward trend since hitting a peak in early May, but there is concern the trend will reverse with the current resurgence in infections.

New infections primarily among young people have been on the rise since a nationwide state of emergency was lifted on May 25, stoking fears that asymptomatic patients and those with mild symptoms could unwittingly spread the virus to elderly family members and communities.

More than 660 new cases of the novel coronavirus were reported Saturday across Japan, the highest since April 11. Tokyo on Monday reported 168 cases bringing its cumulative total to over 9,400, the most among Japan's 47 prefectures. The nationwide total stands at over 25,000, excluding about 700 from the Diamond Princess.

Deaths attributed to COVID-19 rose rapidly through the end of April with hospitalizations increasing as the virus spread. Japan recorded 31 deaths on May 2, its highest number in a day.

"The mortality rate is high in severe cases of the virus, so we must not let our guard down. Those with underlying conditions should be careful," said Tsuneo Morishima, visiting professor at Aichi Medical University.

New fatalities were increasing at a rate of over 200 per month, but the pace started to slow after the death toll topped 950 in mid-June. It took over a month for the number to reach 1,000.

The health care system is currently not overwhelmed as young people, who tend to only experience mild symptoms, have made up the bulk of new infections in recent days, experts said.

The nationwide death toll stood at 981 as of July 15, excluding those from the Diamond Princess, according to data from the health ministry.

Those 60 and older, who are prone to developing severe symptoms of the virus, made up over 90 percent of the deaths, with those in their 80s and above accounting for 556 deaths, followed by 268 deaths among those in their 70s and 101 deaths among those in their 60s.

Globally, the United States has the highest coronavirus death toll at over 140,000, followed by Brazil at over 79,000 and Britain at over 45,000.