The University of Tokyo ranked eighth for high-quality natural science research in 2020, returning to the top 10 after falling to 11th the year before, according to a survey by research publisher Springer Nature Group.

In the list of 500 global institutions, topped by the Chinese Academy of Sciences, five other Japanese universities and a scientific research institute ranked among the top 100.

Although researchers have had to deal with laboratory closures and disruptions to experiments amid the coronavirus pandemic, a surge of articles related to COVID-19 contributed to an overall increase in research output in 2020, said the German-British academic publishing group.

Kyoto University and Osaka University ranked 37th and 65th, respectively, in the latest survey based on institutions' contributions to research articles published in 82 natural science journals that are chosen by an independent group of researchers.

Among other high-ranking Asian institutions were the University of Science and Technology of China in 11th place and the National University of Singapore in 29th.

In the ranking of institutions that achieved significant increases in research output in the 2019-2020 period, dubbed "rising stars," Japan's Riken state-sponsored research institute secured seventh place, while Nagoya University was 10th.

Japan was the fifth leading country in terms of research output, following the United States, China, Germany and Britain.