Mr. Mittal and Mr. Ruia were summoned by the CBI court on April 11 as accused along with Asim Ghosh, the former head of Vodafone-Essar, and former telecom secretary Shyamal Ghosh.
Mr. Mittal moved the Supreme Court on April 1 for quashing the order against him. Mr Ruia too challenged the CBI court order on April 9. The apex court had last week directed the CBI court to postpone its summons to Mr. Mittal till April 16.
The CBI court in its summons had said that Mr Mittal, Mr Ruia and Mr Ghosh were "prima facie" in "control of affairs" of their companies which were named in the charge sheet by the CBI in the case.
Mr. Mittal, Mr. Ghosh and Mr. Ruia were named as the accused because "they represent the directing mind and will of each company", Judge O.P. Saini had said in his order.
Bharti had said at that time that while it was "saddened" at the summons being issued, it would "fight" the charges.
The CBI had filed a charge sheet on December 21, 2012, against Mr Ghosh and three telecom firms -- Bharti, Hutchison Max Telecom Pvt Ltd (now known as Vodafone India Ltd) and Sterling Cellular Ltd (now known as Vodafone Mobile Service Ltd).
The CBI probe concerns alleged irregularities in allotting mobile spectrum in 2002 during the NDA government. At the time, Pramod Mahajan, now deceased, was telecom minister.
The investigation follows a scandal over airwave allocations in 2008 by then telecom minister A Raja, who was jailed for allegedly accepting kickbacks in return for assigning under-priced licenses to mobile phone operators for second-generation or 2G airwaves. The 2G scam, as it's referred to, shook Dr Manmohan Singh's government after the national auditor said it was worth Rs. 1.76 lakh crore.
With inputs from agencies