NEW DELHI: Finance minister Pranab Mukherjee on Tuesday said investigative agencies found nothing during their probe of the alleged security breach at his office in the North Block, PTI reported.Commenting on the reports of a possible breach of security in his and other senior officials' offices, Mukherjee told reporters on the sidelines of function, "In respect of news item, IB investigated into it and they found there is nothing."According to a media report, Pranab Mukherjee had written to Prime Minister Manmohan Singh last year asking him to order a secret inquiry into the serious breach of security in his office.On September 7, 2010, the finance minister wrote to the Prime Minister asking him to order a "secret inquiry" about the presence of "planted adhesives" in 16 key locations in his office, the newspaper Indian Express reported.These locations included the office of Mukherjee himself, the office of his adviser, the office of his private secretary Manoj Pant, and two conference rooms used by the finance minister.However, in his letter to the Prime Minister, Mukherjee mentioned that no "live microphone" or recording devices were found.