The Comptroller and Auditor General, India's national auditor, last year alleged that the coal ministry had given away crores of rupees in windfall gains to 100 private and some state-run firms--sparking a CBI probe into whether kickbacks were paid in exchange.
The scandal has rocked Prime Minister Manmohan Singh's government, with the CBI investigating how the coal ministry, which was headed by Singh from 2004-2009, allocated mining licences.
The CBI last week named Birla, one of country's leading businessmen, as a suspect in its investigation. He was accused of criminal conspiracy along with former coal secretary PC Parakh.
The decision to file a case against Birla was met with protests from business leaders and associations who warned that such actions could harm India's image and scare away foreign investors. Some 14 FIRs--the first step in a police investigation--have been filed during the CBI's probe.