New Delhi: Congress leader P Chidambaram on Thursday said the government's new measure to secure Aadhaar data was meaningless because the damage has been done as millions of citizens have already shared their unique ID number with service providers.

"Under compulsion, millions of persons have already shared Aadhaar number with many service providers. New security layer is like locking the stable after horses have bolted," the former Finance Minister tweeted.

The UIDAI, which collects and manages Aadhaar data including biometrics of citizens, on Wednesday announced a new two-layer system to strengthen security under which citizens would no longer be required to share their unique IDs for verification purposes.

This was done to address privacy concerns after a news report claimed a breach in the Aadhaar database.

Under the new system, at the user-end, the Aadhaar holder will have the choice not to share their Aadhaar number at the time of authentication.

Instead, a random 16-digit Virtual ID number would be generated and could be used in lieu of Aadhaar with the authorised agency like banks and telecom service providers.