The Central Bureau of Investigation is probing Idea Cellular and the Tatas for alleged violations of licence conditions in 2005-2006.

CBI officials say their investigation has been spurred by the similarity of these lapses to those allegedly committed by Swan and Reliance Telecom, whose executives have been arrested. The officials said they are also examining what an official described as the telecom department''s "failure" to act against Idea and the Tatas.

. In case of Idea, the investigation is at an initial stage and the CBI is yet to file formal charges or even register a first information report.

The investigators are focused on the validity of an application filed by Idea Cellular for the Mumbai circle in August 2005. At that time, both Tatas as well as the Birla Group owned more than 10% in the company. The CBI thinks that the Idea Cellular application was invalid and should have been promptly rejected, as the Tatas were already operating CDMA-based mobile services in Mumbai. Acceptance of the application was not possible as it would have resulted in Tatas having more than 10% stake in two telcos operating in the same area, something not permitted by Indian telecom regulations.

Instead of being immediately rejected, the application was put on hold till Idea Cellular became compliant after the Tatas exited the company in 2006.

A spokesperson for Idea Cellular said that company was not aware of any probe. "However, the suggestion that Idea has ever been favoured by the DoT shows lack of familiarity with facts. When Idea applied for the Mumbai licence, it was alone in the queue, and there was no competition. The question of being favoured does not arise," the company said in response to an email query.

A spokesperson for Tata Teleservices said they would not comment for the story.

A one-man committee appointed by the telecom department to probe the allocation of mobile permits since 2001 had unearthed what it termed as violations in case of Tatas and Idea Cellular. Justice Shivraj Patil's report, submitted to the DoT earlier this year, said that Idea Cellular did not fulfil the eligibility criteria on the date of application, but had retained its priority in the queue for mobile permit and airwaves in the Mumbai circle based on this date. The report also adds that DoT failed to get Idea to make a fresh application for Mumbai after Tatas had exited the company.

The report blamed five DoT officials for the violations. "Having adopted policy of First-Come-First-Serve, grant of extension (to Idea) for acquiring eligibility subsequent to the date of application, while maintaining priority (for Idea), went against the principle of FCFS as even ineligible applicants could book priority merely by making an application. The officials mentioned are responsible for such lapse," Justice Patil's report added.

'Similarity' with ADAG-Swan

CBI officials told ET that failure to act against telecoms department officials as well as Tatas and Idea could weaken their case against Swan and Reliance Telecom. "We don't want Swan Telecom to cite this precedent in its own case," an official in the agency told ET, seeking anonymity, because of the sensitivity of the matter.

Reliance Telecom has been implicated because it allegedly controlled Swan Telecom at the time the latter had applied for licenses violating the rule which prevents a mobile phone company from owning more than 10% stake in another.