The Union government on Friday asked Research and Analysis Wing, Intelligence Bureau and the Delhi Police's anti-terrorism and espionage wing to participate in the investigations into the theft of 15 computer hard disks from the Defence Research and Development Organisation.

The disks are believed to contain information regarding assessment of Pakistan's nuclear and missile capabilities, police sources said.

Defence Minister George Fernandes, however, said 'no vital information' had been lost in the theft. The disks were stolen from Scientific Analysis Group and Institute of System and Analysis and came to light on Monday.

He said the DRDO had launched an internal probe into the incident.

Defence ministry officials also insisted that nothing of 'strategic nature' or anything dealing with the Nuclear Command had been stolen.

"Only internal data exchange and data relating to human resources and library" has been stolen in the break," they said.