The CBI, which is probing the 2G spectrum scam , has sought telecom regulator TRAI''s help to ascertain the loss to the government on allocation of spectrum to all operators between 2001 and 2008. 

Highly placed sources in the agency said the decision to approach TRAI was taken in view of the fluctuating estimates of the losses to the exchequer on account of the sale of spectrum in 2008. 

"We have requested TRAI to set up an expert team which will go into the entire gamut of spectrum pricing and give us an estimated loss which could be proved in the court of law," a senior official of the agency said. 

Confirming the CBI's communication, sources in TRAI said that it has forwarded the request to a team of experts and the report is expected soon. 

"As soon as we get the report from experts, the same will be forwarded to the CBI," sources said. 

This comes within days of TRAI recommending a pan-India licence fee of Rs 10,972.45 crore for 6.2 Mhz of start-up spectrum with effect from April 1, 2010, as against the Rs 1,658 crore that was being paid by operators till now. 

TRAI had also recommended that each Mhz of additional spectrum held by operators should cost a one-time fee of Rs 4,571.87 crore (all-India), though it would vary from circle-to-circle and the operators would only have to pay for those zones where they hold extra spectrum. 

The CBI had earlier said the government may have lost over Rs 22,000 crore due to irregularities in the allocation of spectrum in January, 2008, by former Telecom Minister A Raja, who was arrested earlier this month on charges of favouring some private firms. 

Later, the investigating agency had estimated the loss at around Rs 50,000 crore, as estimated by the Enforcement Directorate . 

An expert panel of Trai has valued the price of 2G spectrum beyond the 6.2 Mhz start-up spectrum given to operators 136 per cent higher than the auction bid for 3G spectrum on a pan-India basis. On the other hand, the value of 2G spectrum within the limit of 6.2 Mhz was 53 per cent of the 3G price. 

However, the CBI was unable to discern the price of 2G spectrum allocated to telecom players between 2001 and 2008, when most of the old players like Bharti, Vodafone and Idea were allocated spectrum. 

Trai has forwarded the request for assessment of the value of spectrum price to its expert panel, as asked by the CBI.