NEW DELHI:

leader

on Tuesday termed mandatory linking of

"threat to national security" and said he'd written a letter to Prime Minister

expressing his concerns regarding the same.

"I am writing a letter soon to PM detailing how compulsory Aadhaar is a threat to our national security. SC will, I am sure, strike it down," Swamy said in a post on Twitter.

The

MP's tweet came a day after the

asked the Centre to respond to a on a petition challenging the proposed linking of mobile phones with Aadhaar. The top court also said its constitution bench will start hearing a clutch of petitions challenging the government's move to make Aadhaar card a must for availing benefits of various social welfare schemes.

In the past too, Swamy has critized Aadhaar for being intrusive and susceptible to abuse, particularly by foreign intelligence agencies.

He had said the government's decision to use an American company to develop some core software for the Aadhaar system may raise issues regarding the data's security, making it prone to US intelligence agencies who may use the information for their vested interests.

Recently, a nine-judge constitution bench of the apex court had held that Right to Privacy was a Fundamental Right under the Constitution. Several petitioners challenging the validity of Aadhaar had claimed it violated privacy rights.

Swamy had welcomed the judgment and said that right to privacy is a fundamental right under Article 21 of the Constitution.

"Now onto Aadhar modification," he had tweeted.

The Centre had on October 25 told the Supreme Court that the deadline for mandatory linking of Aadhaar to receive the benefits of government schemes has been extended till March 31, 2018 for those who do not have the 12-digit unique biometric identification number and were willing to enroll for it.

(With inputs from PTI)