Japan's nationalist Prime Minister Shinzo Abe is to visit Tokyo's controversial Yasukuni war shrine on Thursday morning, his office said.

"The office is aware that the prime minister plans to visit the shrine today," said a spokesman at the Prime Minister's Office, adding that it was not a matter that was being officially announced.

The visit will come exactly one year after he took power and is expected to further inflame already-tense relations with China and South Korea.

The shrine is the believed repository of the souls of Japan's war dead, including several high-level officials executed for war crimes after World War II, who were enshrined in the 1970s.

South Korea and China see it as a symbol of Tokyo's unrepentance and a misguided view of its own past.

The last incumbent Japanese prime minister to visit the shrine was Junichiro Koizumi on August 15, 2006, the anniversary of Japan's defeat in 1945.

Several members of Abe's cabinet have been to the shrine over the last year, and have previously claimed they were doing so in a personal capacity.

The form of confirmation from the prime minister's office suggests Abe may also be trying to make the same distinction.