Amid the political fundraising scandal involving the arrest of party President Ichiro Ozawa's chief secretary, Democratic Party of Japan executives are calling for a rule barring companies that bid on public works projects from donating to political parties.

"If we make (a new rule), it has to be effective. And we will aim to create something that the ruling parties can possibly agree on," Katsuya Okada, a DPJ vice president and chief of the party's political reform team, told reporters Friday.

But Okada, who was the DPJ president before Ozawa, cautioned that the scope of such a ban would be hard to delineate because the degree of involvement with public works projects ranges widely and most firms could be affected.

When Okada led the DPJ, the party's manifesto for the 2004 Upper House and 2005 Lower House elections called for a total ban on political donations from companies receiving public works orders. But the policy was not included in the platform for the 2007 Upper House election under Ozawa, who stressed transparency regarding the sources of political funds.

During a news conference Tuesday, Ozawa, allegedly the recipient of illicit Nishimatsu Construction Co. donations, said the ban is one idea, but it would be hard to impose because most companies do business with the government to some degree.