"... All these premises (in Finance Ministry) have been subjected to regular screening. During these exercises, no devices have been detected," Minister of State for Finance SS Palanimanickam said in a written reply to the Rajya Sabha.
He said that security checks are periodically conducted in the Ministry of Finance and the Finance Minister's Office.
One such routine security check was conducted on September 4, 2010, by the Investigation Directorate of the Central Board of Direct Taxes (CBDT), which engaged the services of an expert with domain knowledge of the subject, he added.
During the check, adhesive-like substances were noticed at various locations, Palanimanickam added.
"This was brought to the notice of the Prime Minister by the Union Finance Minister in September, 2010," he said.
Subsequently, the Prime Minister directed the Intelligence Bureau to conduct a secret inquiry into the matter.
"Adhesive patches were found stuck at a few places. The adhesive patches were subjected to chemical/forensic analysis, which revealed that the substance contained contents comparable with contents of chewing gum," the minister added.
Physical examination of the recovered substance did not reveal any sign or mark suggestive of any device having been attached thereto.