The Supreme Court on Friday sought the Centre's response to a plea challenging the implementation of the 'AADHAAR' scheme, aimed at providing a unique identity number to all Indians, without any legislative nod.

A bench comprising Chief Justice Altamas Kabir and Justice J Chelameswar issued notice to the Ministry of Finance, Planning Commission and the Unique Identification Authority of India (UIDAI), set up to implement the scheme, seeking their replies on the contention that the Parliament was "circumvented" in implementation of the scheme.

The public interest litigation petition, filed by retired Karnataka High Court judge, Justice K S Puttaswamy and advocate Parvesh Khanna questioned the government's decision of issuing AADHAAR numbers to citizens while the National Identification Authority of India Bill, 2010 is pending before the Rajya Sabha where it was introduced on December 3, 2010.

The Bill, for the purpose of giving legal backing to the scheme, was referred by the Rajya Sabha to the Standing Committee (Finance) which had rejected it by overwhelming majority on December 11, 2011, the petitioners have said.

"Whether the executive power vested in the Union under Article 73 of the Constitution can be exercised by avoiding the consideration of a Bill on the same subject pending before the Parliament and after its rejection by the Standing Committee.. and circumventing the Parliament?", the plea asked.

The petitioners in their plea have sought directions to the government to prevent it from acting upon its notification of January 28, 2009 and from by-passing or circumventing the passage of the Bill by Parliament after discussion, debate and voting.

The government through its notification of January 28, 2009 had set up the UIDAI for issuance of AADHAAR numbers and cards to all Indian citizens.

The UIDAI would maintain a database of Indian residents, containing their biometric and other details.