The chief secretary of Ichiro Ozawa, head of the Democratic Party of Japan and a leading candidate to be the next prime minister, was arrested March 3 on suspicion of accepting illegal corporate donations, prosecutors said.

Democratic Party of Japan President Ichiro Ozawa exits DPJ headquarters March 3 in Tokyo's Nagatacho district. KYODO PHOTO

Takanori Okubo serves as chief accountant of Ozawa's political body, Rikuzankai, which allegedly took money from scandal-tainted Nishimatsu Construction Co., according to investigative sources.

Ozawa is in line to become prime minister if his party wins the next general election, which must be held by autumn.

Rikuzankai allegedly got the funds from two groups headed by an ex-Nishimatsu official, breaking the political funds control law, the sources said.

Corporate donations are prohibited by law except to political parties or their organizations for managing political funds.

The law also prohibits donations made under the name of another person or body.

Experts said Okubo's arrest deals a blow to the DPJ, which is attempting to promote itself as a viable alternative to the ruling Liberal Democratic Party while the LDP's leader, Prime Minister Taro Aso, is suffering from historically low public support ratings.

Meanwhile, DPJ lawmakers said March 4 that Ozawa will stay in his post despite the arrest of his secrtary for allegedly violating the political funds control law.

"As I have dealt with (the political funds) in accordance with the law, there is not a problem," Ozawa told party executives at an emergency meeting March 4.