Prosecutors have apparently decided not to question Democratic Party of Japan President Ichiro Ozawa on a voluntary basis in connection with alleged illegal donations from Nishimatsu Construction Co., investigative sources said Friday.

The prosecutors, at least for now, have judged it difficult to accuse Ozawa of failing to properly supervise his top secretary, Takanori Okubo, 47, who was arrested earlier this month on suspicion of taking illegal corporate donations from organizations linked to Nishimatsu, the sources said.

Other media reports also indicated that prosecutors have found no evidence to prove Ozawa played a role in the illicit donations.