The CBI today told the Supreme Court that it was not in a position at this stage to "deny or agree" with allegations of a Rs 70,000-crore scam in allotting 2G spectrum licences in 2008 in which telecom minister A Raja's name has cropped up.

An affidavit in this regard was filed by the agency in a sealed envelope in compliance with the September 13 notice to the Centre, Raja and others.

Sources associated with the matter said the Central Bureau of Investigation (CBI) was "cautiously" moving in the case and at this stage it was not in a position to agree or deny the allegations as the probe was still going on. "We do not agree or deny anything till the investigation is going on," sources said.

A bunch of petitions filed by an NGO, Centre for Public Interest Litigation (CPIL) and others had alleged that the Centre was trying to put a lid on the investigation into the alleged irregularities in spectrum licence allocation.

The Supreme Court on September 13 had sought response within ten days from Raja, Department of Telecom, CBI, Enforcement Directorate and the Income Tax department. Raja, his ministry and others are yet to respond.

The CBI counsel today made a mention of filing its reply before a bench comprising Justices G S Singhvi and A K Ganguly which had wanted to know how the CBI did not know against whom the investigations were on, despite continuing the process for several months and filing an FIR against unknown telecom ministry officials.

"FIR is against the unknown officials of DoT... Why they are still unknown. Does CBI not know who the officials are?" the bench asked expressing concerns over the investigation done by the CBI.

The petitioners have alleged that certain public servants, middlemen, corporate lobbyist Niira Radia were involved in the conspiracy for granting Unified Access Service (telecom) licences.

The petitioners have challenged the May 25 order of the Delhi High Court, which had dismissed their petitions. They have urged the apex court to call for the entire records of investigation from CBI and the Enforcement Directorate into the alleged 2G spectrum scam and direct them to produce regular and periodic status reports.

The petitioners, including telecom watchdog, an NGO, and an individual, submitted the transcript of an alleged conversation between Raja and Radia, who heads Vaishnavi Corporate Communications, to substantiate their charges of nexus that influenced granting of licences.

"The entire investigation has been effectively scuttled. Radia, whose conversation tape with telecom minister has been available with CBI for about nine months, has not even been called for questioning," the petition said. The petitioners also produced several communications, including from Prime Minister Manmohan and the then Finance Secretary and others, to Raja asking him to ensure that 2G spectrum was allocated in a fair, transparent and efficient manner.

The petitioners alleged that the DoT, under the ministership of Raja, had given away 2G spectrum to 122 operators at a throwaway price of Rs 1,658 crore for pan-India licences on a first-come-first-served basis in January, 2008.

Raja was expected to take the auction route for allotting the 2G licences to telecom service providers, they said.