Facebook's new facial recognition feature, which was launched to make it easier for users to find one another, has pressed regulators and privacy advocates to raise privacy concerns.

Privacy advocates warn that Facebook’s facial recognition technology could be used to track people down, and access their personal details without their permission.

The Electronic Privacy Information Center and a number of other advocacy groups filed complaints with the United States Federal Trade Commission against Facebook's use of the controversial technology.

Complainants urged the Federal Trade Commission to order Facebook to stop using the new feature.

Massachusetts Representative Edward J. Markey said that Facebook must have made the controversial feature “opt-in” for users.

Speaking on the topic, Markey said, “If this new feature is as useful as Facebook claims, it should be able to stand on its own, without an automatic sign-up that changes users' privacy settings without their permission.”

Facebook Chief Executive Mark Zuckerberg has so far not issued any statement in response to the new concerns.