Japanese Prime Minister Shinzo Abe entered a Tokyo hospital on Monday for an examination but a detailed reason for the visit was not immediately known, local media reported.

Government sources said it was not a worrying situation, Nippon TV reported, while Kyodo News cited people near to the prime minister as saying it was for a regular check-up.

Abe's office did not immediately respond to a request seeking comment.

The reports follow weekend comments by the ruling Liberal Democratic Party's tax panel chairman, Akira Amari, that he was concerned about Abe, 65, suffering from fatigue for his continuous work responding to the coronavirus crisis.

"I want him to take a break. He has a strong sense of responsibility and feels it's wrong to take a break," Amari told a news program on Sunday.

Abe, Japan's longest-serving prime minister, has been in power since 2012 in his second time as premier.

He resigned from his first stint in 2007 due to struggles with ulcerative colitis, which he now keeps under control with medication that was not previously available.