The Intelligence Bureau has barred the use of mobile phones with cameras and Bluetooth connectivity and computer devices like pen drives by its operatives, sources said.

The decision comes close on the heels of the detection of a spy ring in the National Security Council Secretariat.

The IB, whose counter-intelligence wing is probing the alleged leak of classified information from the NSCS to an American diplomat, recently took steps to ensure that its operatives and officials were complying with an earlier directive barring them from using mobiles with sophisticated features, the sources said.

Cellular phones with cameras, in-built memory for storage of data, and Bluetooth and infrared connectivity that allow wireless transfer of data from computers are barred.

"Even officials are using basic mobile phone models that cost a few thousand rupees," said a source.

As its sleuths are uncovering the network involved in leaking sensitive data on the country's future policies from the NSCS to American diplomat Rosanne Minchew, who has since left the country, the IB's top brass recently ordered the removal of a variety of CD-drives from computers in its main office.

Special steps were taken to remove all drives capable of recording on CDs, the sources said.