Authorities arrested the president of Suth Korea's KTF last week after allegations his company was bribed by suppliers in return for buying their products.
A Dow Jones report, quoting Yonhap news agency, also said KTF president Cho Young-ju was detained at the Seoul Central District Prosecutors' Office hours after investigators confiscated contracts and computer hard disks from the company's headquarters.
Cho and several KTF executives are accused of taking kickbacks from suppliers over the past four years, the report said.
Investigators said they found evidence that Cho opened back accounts under borrowed names to accept the rebates, which also might have been sent to politicians as bribes, it said.
Investigators believe the suppliers created slush funds for KTF by inflating the sale prices of their goods, Yonhap said.
An unnamed KTF official said Cho's arrest was 'embarrassing,' Yonhap reported.