The Central Bureau of Investigation said on Thursday that Swan and Unitech were given preferrential treatment in the awarding of mobile phone licences in a sign a corruption scam could spread to the business world.
The Central Bureau of Investigation arrested former telecoms minister Andimuthu Raja on Wednesday over alleged irregularities in the allocation of mobile licences and radio spectrum.
Norway's Telenor owns a majority stake in Unitech Wireless. UAE's Etisalat owns about 45% of Swan, which has since been renamed as Etisalat DB. Both companies have denied any wrongdoing.
The statement by a CBI lawyer came during a court hearing into the alleged corruption case.