The Supreme Court on Monday pulled up West Bengal for questioning the Centre’s decision to make the 12-digit biometric Aadhaar number mandatory for availing social welfare schemes, saying it was against the federal structure.

The Bengal government, which is at loggerhead with the Centre, had filed the petition on October 28.

“In a federal state, how can one state government challenge a law passed by Parliament. There is no doubt it (Aadhaar) needs examination but the prayer can’t be entertained,” said the court, which is hearing a bunch of petitions against Aadhaar.

The Mamata Banerjee government was the latest to join the debate against Aadhaar that has been challenged on various grounds, including violation of privacy.

Bengal’s move was against federal structure, the court said, adding , “Tomorrow the Centre can challenge a law passed by the state.”

Appearing for the Bengal government, senior lawyer Kapil Sibal said they challenged Aadhaar as it effected payment of subsidy to children.

He offered to amend the prayer and said they would not challenge the Aadhaar law.

In a separate petition, the court issued a notice to the government over a plea by a student opposing linking of Aadhaar to mobile phones.

The Centre is expected to tell the court in the afternoon that it was willing to extend to March 31 the deadline for linking Aadhaar to various welfare schemes, bank accounts and mobile phones.