Japan has slipped to 12th place internationally in the number of scientific papers cited as references. The number of citations is often seen as an indicator of the quality of research papers.

Japan's National Institute of Science and Technology Policy analyzed scientific papers covering 22 natural science areas, such as biology and physics, published from 2018 to 2020.

Japan had an average of 3,780 papers per year in the top ten percent of the most-cited papers. The number itself was a slight increase but the ranking slipped from 10th a year ago.

It is the first time that Japan has missed the top 10 since 1981, when analysis began.

In terms of publications, Japan accounted for an average of 67,688 papers per year, down one place to 5th.

Education ministry officials say Japan's impact in the natural sciences is waning.

They say funding for research at Japanese universities has seen a smaller increase during the past 20 years compared to other major countries.

They added that researchers are having difficulty securing enough research hours.

They also noted that the number of students receiving doctorate degrees has been on the decline in Japan, while the number has doubled in the United States, China and South Korea over the past two decades.