General contractor Kajima Corp. told a smaller construction company that it needed consent from the office of Democratic Party of Japan kingpin Ichiro Ozawa to become a subcontractor for a government dam project in Iwate Prefecture in 2004, sources said Thursday.

Prosecutors, who Wednesday searched the offices of Ozawa, now DPJ secretary general, and Kajima as well as other locations over accounting irregularities allegedly handled by a former Ozawa secretary, suspect Mizutani Construction Co. donated funds to Ozawa to gain the necessary consent, dubbed the "voice from heaven," the sources said.

Mizutani, based in Kuwana, Mie Prefecture, is taking part as a subcontractor in a project to build the dam's main structure in Iwate's Oshu City in Ozawa's home district. The project was awarded to a Kajima-led joint venture in October 2004.