Liberal Democratic Party President Shinzo Abe receives applause from the LDP lawmakers shortly after his name was called as the winner of the ruling party presidential elections at its headquarters in Tokyo. Picture: Koji Sasahara/AP

Tokyo - Japanese Prime Minister Shinzo Abe was re-elected as head of his Liberal Democratic Party (LDP) on Thursday, despite his involvement in a series of scandals.

The victory in the ruling party's presidential election is tantamount to winning the prime ministership.

The 63-year-old hawk, who was running for a third three-year term as LDP leader, easily defeated former defence minister Shigeru Ishiba in the two-man race, with about 82 per cent of the party's lawmakers voting for the premier.

"I would like to work on constitutional change with you," Abe told LDP lawmakers after his victory.

Unhappily for Abe, the race was overshadowed by a summit meeting in Pyongyang between North Korean leader Kim Jong Un and South Korean President Moon Jae In - Abe has gained popularity by bashing the two countries and China.

The Japanese leader has struggled to improve relations with China and South Korea since he took office in December 2012, due to territorial disputes and differing views of wartime history.

On the domestic front, Abe has also faced down a series of scandals.

He has been accused of having wielded his influence to help his long-time friend Kotaro Kake open a veterinary school in the western city of Imabari at a time when universities have struggled to attract students amid low birthrates in Japan.

The premier denied having instructed government officials to favour the department run by Kake at the Okayama University of Science.

And in March, the Finance Ministry acknowledged it had falsified documents related to a deal struck in June 2016 to sell public land to nationalist school Moritomo Gakuen at just 14 per cent of its appraised price.

The name of Akie Abe, the premier's wife, who served as honorary principal for the school, had appeared in the original documents but was deleted, local media reported. She quit the post soon after the scandal surfaced in February 2017.

Abe has said he will "quit as prime minister and lawmaker" if he or his wife were found to have been involved in the land deal.