"Ministry of Home Affairs' objection against the companies are very serious. They can become threat to internal and external security of the nation. You get huge FDI for compromising national security," a bench of justices GS Singhvi and A G Ganguly asked.
The court was referring to service providers Etisalat DB Telecom and S-Tel against whom Home Ministry had expressed reservation.
"There is a security angle to it and if it turns out to be true then it means that security aspect has been compromised," the bench said.
"We are not experts in these matters. But if these things are not taken care of then they can even know Army operations of the country," the bench said.
The court was hearing a petition filed jointly by various civil societies, including Centre for Public Interest Litigation, Telecom Watchdog and Common Cause,and by Janata Party President Subramanian Swamy seeking court's direction to cancel all the licences issued to service provider during Raja's tenure.
Several eminent persons like former Chief Election Commissioners JM Lyngdoh, TS Krishnamurthy and N Gopalaswami and former Central Vigilance Commissioner P Shankar are also petitioners in the case.
Earlier on March 3, the bench had ordered the CBI to probe the restoration of 2G spectrum licence to Chennai-based telecom operator S-Tel after its cancellation earlier on grounds of threat to national security.
It had also asked the agency to investigate UAE-based Etisalat as the Home Ministry had expressed reservations earlier to the Department of Telecommunication and the Union Finance Ministry regarding the foreign direct investment made by it in the telecom sector.