Two ruling party lawmakers who received political funds from scandal-tainted Nishimatsu Construction Co. denied any wrongdoing Friday but said they have decided to return the money for ethical reasons.

Prosecutors have begun examining contributions Nishimatsu made to a Liberal Democratic Party faction headed by Economy, Trade and Industry Minister Toshihiro Nikai, it was revealed Friday.

"There is absolutely no reason for a special investigation," Nikai told reporters Friday, denying he had engaged in any illegal activity.