A company in Tokyo linked to Nishimatsu Construction Co., the builder at the center of a widening political scandal, leased an office and provided dubious donations to industry minister Toshihiro Nikai, sources alleged Thursday.

The Nishimatsu scandal, which has led to the indictment of a key aide to Democratic Party of Japan President Ichiro Ozawa, barely touched the ruling Liberal Democratic Party in its early stages. But that appears to be changing amid increased scrutiny of the charges and the timing of the indictment, which hit the opposition party before a general election that must be held by autumn.

Since around 1999, a political fundraising body operating on behalf of Nikai, a seasoned LDP legislator, has been paying more than ¥2 million a year to the affiliated company to rent an apartment in Osaka, Nishimatsu and other sources said.

Nishimatsu, meanwhile, has given about ¥3 million in donations annually to a local LDP chapter in Wakayama Prefecture led by Nikai since 2006, the sources said. Wakayama is his power base.

Nikai's political funds reports contain no records stating the donations were from Nishimatsu, because the donations from the Tokyo-based construction firm, OA Engineering, were made in payments of ¥50,000 or less and under the names of its employees and other people, the sources said.

The names of individual donors who give ¥50,000 or less do not need to be recorded in political funds reports.