A majority of Japanese firms want Prime Minister Shinzo Abe to finish his current term to September 2021 but fewer than one in five say he should stay beyond then, a Reuters poll has showed as allegations that he broke campaign laws erode public support.

Opposition lawmakers allege Abe favored supporters with invites to an annual state-funded cherry blossom-viewing party and may have broken campaign laws by subsidizing backers' attendance at a reception the night before. Questions have also arisen over whether a gangster attended the state-funded event and why this year's invitation list was shredded.

The prime minister has denied any wrongdoing.