Facebook has spoken out against businesses that demand Facebook usernames and passwords from their employees and prospective hires.

“In recent months, we’ve seen a distressing increase in reports of employers or others seeking to gain inappropriate access to people’s Facebook profiles or private information. This practice undermines the privacy expectations and the security of both the user and the user’s friends. It also potentially exposes the employer who seeks this access to unanticipated legal liability,” Facebook chief privacy officer Erin Egan writes in a Friday blog post.

“If you are a Facebook user, you should never have to share your password, let anyone access your account, or do anything that might jeopardize the security of your account or violate the privacy of your friends.”

Reports of such practices are widespread. In June 2009, the city of Bozeman, Montana made headlines when it was revealed that its job applications forms asked for usernames and passwords for the job seekers accounts on “social networking,” including everything from Facebook and Twitter to YouTube and Google. Earlier this year, the American Civil Liberties Union took aim at the Maryland Department of Corrections after it asked a Maryland man for his Facebook credentials during a recertification interview. And just this week, the Calgary Herald reported on a similar incident in Canada.