The CBI registered the case on Friday under several sections of the Information Technology Act against unknown public servants and others on the basis of a letter from the Karnataka government dated August 20.
According to the state government order, the CBI was asked to probe associates and relatives of political leaders belonging to the ruling and the opposition, besides government servants whose phones were tapped.
A CBI official told : "A team of CBI official has gone to Bengaluru to collect all the related documents related to the probe into illegal phone tapping case from the Karnataka Police."
The order further said that because of illegal phone tapping in the state, it is apprehended that crucial and personal information of many senior political leaders and government servants might have been leaked, which is likely to infringe upon their right to privacy.
The CBI action comes after Karnataka Chief Minister B.S. Yediyurappa earlier this month had recommended a CBI probe into the allegations that the phones of several Opposition leaders, ruling party leaders, their relatives and public servants were illegally tapped during the previous JD-S-Congress regime in the state.
"All political leaders, including Congress Legislature Party (CLP) leader Siddaramaiah, has sought a high-level probe into the scandal. So I have ordered a CBI probe into it," Yediyurappa had said in Bengaluru.
After the leak of an alleged intercepted conversation, the Bengaluru Police also registered an FIR on August 19. Joint Commissioner (Crime Bengaluru) Sandeep Patil also submitted an interim report, suggesting a high-level probe into the matter.
Former Chief Minister Kumaraswamy has been accused of sanctioning phone tapping during his tenure when his government was facing crisis after a series of resignation by 17 MLAs of then ruling combine of Congress and Janata Dal-Secular. Kumaraswamy had denied the charge.
( With inputs from IANS )