Kajima Corp. and other companies paid a combined 900 million yen in rebates to construction firms linked to a former executive of Takeda Pharmaceutical Co. for contracts to build a pharmaceutical plant in Hikari, Yamaguchi Prefecture, according to a tax audit obtained Tuesday.

The Tokyo Regional Taxation Bureau found that Kajima and others that received the 10 billion yen order to build the plant paid the 900 million yen in return for the contracts. It ruled the rebates are taxable and not a tax-free expense as claimed, according to the investigation.

The tax bureau is expected to order Kajima and the others, including engineering firm Shinryo Corp., to pay back taxes and penalties on the rebates.

Kajima, Shinryo and others paid the money to construction companies linked to the former Takeda executive, calling them consignment and commission fees, but there were no such transactions, the investigation showed.

The Takeda-linked construction companies hid the income from the rebates with losses claimed on their tax statements, but the tax bureau determined the losses were fictitious and the companies thus failed to declare 2 billion yen in taxable income.

Kajima declined comment on the case.

Takeda, one of the country's top pharmaceutical firms, said it will conduct an internal probe but declined further comment.

The factory in Hikari has been Takeda's flagship plant since 2003, when it began to consolidate its operations.