The supreme court today 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.

The apex court also asked the agency to investigate the antecedents of the UAE-based Etisalat against which 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.

A bench of justices G S Singhvi and A G Ganguly asked the CBI to apprise it of their findings on March 15.

Senior advocate K K Venugopal, appearing for the CBI, however, said as the issues concerning the two firms did not directly relate to the 2G spectrum allocation, the agency may take some more time to complete the probe.

Attorney general Goolam E Vahanvati, meanwhile, explained to the bench about the telecom policy adopted since 1994 and said the spectrum was allocated on the basis of the policy decision which does not envisage its allocation by auction.

He further said the licences cannot be cancelled only on the ground that the policy of auction was not followed. He said there werew faults or gaps in implementation of the policy, it is for the court to take a view.

Vahanvati said that a joint parliamentary committee and the public accounts committee too were looking into the issue of the spectrum allocation and were also examining the CAG report on it.

The attorney general said the matter was also being probed by the CBI on the direction of the apex court, which is also monitoring the investigation.

The apex court had detected yesterday the cancellation and subsequent restoration of 2G spectrum licence to S-Tel, while examining a relevant government file on the matter.

The file was placed before the bench on its direction after it was alleged by the petitioners, Centre for Public Interest Litigation (CPIL) that the Centre had adopted "arm- twisting" policy against the company for challenging DoT's policy in 2G spectrum allocation in the court.

"File placed by the additional solicitor general says something more. It tells about a new dimension which is all together different," the court had remarked yesterday, while asking additioal solicitor general Indira Jaising to bring the file on March 3 as well during the hearing on a PIL by the CPIL for probe into the 2G spectrum allocation during former telecom Minister A Raja's tenure.