URAWA, Saitama Pref. -- Police alerted tax authorities Thursday that two Tokyo-based personal computer industry firms allegedly linked to the Aum Shinrikyo cult are suspected of hiding income, investigation sources said Thursday. The National Tax Administration Agency is planning to launch a full-scale investigation and interrogate Aum members in the near future. Depending on the outcome of the investigation, additional taxes may be imposed on the cult, which authorities believe effectively runs the firms, the sources said. The latest move by the Saitama Prefectural Police is part of efforts to unearth the scope and extent of the cult's activities and finances. Police and tax authorities hope the probe will help expose the hidden flow of money to the cult, the sources said. The two shops -- PC retailer Poseidon, in Chiyoda Ward, and computer wholesaler SBR, in Taito Ward -- have been examined by the tax agency in the past. They have since shut down and been effectively dormant since last summer. A shop manager for Poseidon was arrested last July by Saitama police on suspicion that he falsified his address in filing to register a different PC-related company. Saitama police have also searched Poseidon's PC plants in the prefecture and more than 20 Aum-related facilities in Tokyo, Nagoya, Osaka and other prefectures, including SBR offices, the sources said. They have also searched Aum-related offices in Tokyo's Adachi Ward on suspicion that the cult destroyed evidence linked to its alleged PC businesses.