Jessica Guynn

USA TODAY

SAN FRANCISCO — On Monday morning Facebook launched Marketplace on iOS and Android so its 1.7 billion users could buy and sell stuff to each other right inside the Facebook mobile app. Within hours, Facebook users were selling stuff that Facebook says they can't.

Drugs. Animals. Adult services. Weapons. Themselves. Even body parts (and by body parts we mean crotch shots that would make Anthony Weiner blush.) All of which is pretty much the A to Z of stuff that violates Facebook's commerce policy and community standards.

Mary Ku, director of product management at Facebook, apologized Monday night, saying a technical issue prevented the company from identifying posts that violated its policies.

"As a result, certain posts with content that violated our policies were made visible to people visiting Marketplace," Ku said in an emailed statement. "We are working to fix the problem and will be closely monitoring our systems to ensure we are properly identifying and removing violations before giving more people access to Marketplace."

When asked if it was worried about people selling stuff they shouldn't, Facebook told USA TODAY last week that it would take "appropriate action to make Marketplace a safe place for people."