Intelligence Bureau found nothing amiss after its probe into finance minister Pranab Mukherjee's bugging complaint in September last year but the agency increased the frequency of its 'technical sweeping' in high offices since then as a precaution.
As against occasional anti-bugging exercise inside finance ministry, the IB has now included this ministry in North Block as part of its regular 'technical sweeping' work like what it does for its own premises and offices of the PM in South Block and home minister in North Block.
A senior official said, "Taking cue from the finance minister's complaint which later turned out to be a mere alarm, the Intelligence Bureau now does anti-bugging exercise once every two days or at least four-five days a week."
Mukherjee had urged the PM to order a secret inquiry into the "serious breach of security in his office" in the form of "planted adhesives" in 16 locations in a possible surveillance attempt. Though no live microphone devices were found, he had reported it to the PM. The matter was subsequently transferred to IB for probe.
Referring to the investigation and forensic examination which termed the "adhesives" as nothing but "chewing gum", the official said the matter was "closed" in October last year.
At present, IB is doing 'technical sweeping' of PMO and offices of the home minister, home secretary and Intelligence Bureau director, special director and other senior officials almost every day as part of its 'charter'.
"In case of other ministries, the IB does this exercise as and when asked depending on the nature of issues being handled by those ministries. As an exception, the finance ministry is now being covered more frequently," an officer said.
Officials in the IB and home ministry, however, remained tight-lipped about CBDT reportedly using a private detective agency to conduct 'technical sweeping' to find bugs inside the finance ministry last year.