Government officials ratcheted up pressure Monday on Facebook Inc. over its handling of user data, with federal regulators saying they are investigating the social-media giant’s privacy policies and 37 state attorneys general demanding explanations for its practices.

The Federal Trade Commission, in a statement, signaled that its probe of Facebook is broad. Tom Pahl, a top FTC official, said the commission “takes very seriously” recent reports raising “substantial concerns about the privacy practices of Facebook.”

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