The home ministry issues about 7,500-9,000 orders every month for interception of telephones at the request of nine security organisations, the government told the Rajya Sabha on Wednesday.
This means the Union home secretary signs an average of 300 authorisations every day.
"On an average, 7,500-9,000 orders for interception are issued by the central government per month," minister of state for home affairs Gurudas Kamat told Rajya Sabha in response to the question by MP Naresh Gujral.
This is the first time that the government has put a firm number to the authorisations for lawful interception.
A senior government official said home secretaries usually keep aside about half an hour every working day to put their signatures on the request for interceptions, suggesting that it was impractical to expect the senior official to go into the merits of each case.
"Since the requests have been forwarded by director general-rank chiefs of the nine agencies notified under the Indian Telegraph Act, it is assumed that there has been due diligence within the agencies concerned before making the request," the official said.
The official added the low rejection rate of the interception requests was not unique to India.
Home secretary GK Pillai had earlier indicated that an average 6,000 to 8,000 telephones were being tapped by various central agencies at any given time after taking permission from the home ministry.
Government sources said these figures include tapping phones of naxal and insurgent leaders in naxal-affected areas, J&K and the northeast by the Intelligence Bureau.
To other questions on the challenges due to 3G networks and BlackBerry smartphones, Kamat acknowledged that 3G mobile services were more vulnerable to technology-related crimes as 3G mobile services increase the use of data communication through the mobile phones besides the video calls and the normal voice calls.