The Unique Identification Authority of India on Tuesday issued a statement warning people against sharing their Aadhaar number on social media platforms or elsewhere, and posing challenges to others. The Aadhaar authority said that such activities are in contravention of the law.

The warning follows Telecom Regulatory Authority of India chairperson Ram Sewak Sharma’s act of sharing his unique identity number, and asking people to show him how their knowledge of the unique identity number could be used to harm him.

“This advisory has come with reference to some news items appearing on social media reporting few people publicly posting their Aadhaar numbers,” UIDAI tweeted. “Such activities are uncalled for and should be refrained as these are not in accordance with the law. Aadhaar is a unique identity which can be authenticated to prove one’s identity for various services, benefits and subsidies.”

Earlier on Tuesday, Sharma defended his actions, saying that by sharing his Aadhaar number on Twitter last week, he did not imply that others should do the same. His public challenge had led to a backlash on the social media network. Several users claimed that they had obtained Sharma’s personal details, such as his Permanent Account Number and mobile number, using his Aadhaar number.

The UIDAI said the unique identification number is personally sensitive information equivalent to a bank account number or a passport number. “It should be strictly shared only on a need basis for a legitimate use for establishing identity and for legitimate transactions,” UIDAI tweeted. “Indiscriminate and unwanted publication of any personally sensitive information whether Aadhaar or any other, may render the concerned person vulnerable and, therefore, should be avoided.”

“Such activities are uncalled for and should be refrained as these are not in accordance with the law,” it added. The Aadhaar authority also said that using someone else’s Aadhaar number for authentication or any other purpose could amount to impersonation, which is a criminal offence.