On a day Ratan Tata moved Supreme Court against the leak of the 'Radia tapes', the government ordered a probe into the same. Government sources said the decision was taken a few days ago but the formal instructions took time. The Intelligence Bureau and the Central Board of Direct Taxes have been told to ascertain how the tapes — of phone conversations intercepted by the income tax department in 2009, with the approval of home secretary GK Pillai — were leaked earlier this year.

Half-a-dozen central investigative agencies are empowered to tap phones with the home secretary's permission.