Mat Baxter, CEO of Initiative, an Interpublic Group of Cos. Inc.-owned ad agency, said he would advise his marketer clients to "stay off" Facebook Inc. "entirely," following reports the social media giant gave intimate information on users to third parties without approval.

"It's about time we take a collective stand against the egregious behavior of Facebook," Baxter said in a post on his LinkedIn Corp. profile. The post prompted a statement from IPG CEO Michael Isor Roth, who said the company will continue to work closely with its media partners, including Facebook, according to a Dec. 20 report by The Wall Street Journal.

A spokesman for IPG Mediabrands said Baxter's comments were his own and do not represent the network or the company.

"We have a strong partnership with IPG agencies around the world and look forward to that continuing for years to come," Carolyn Everson, vice president of global marketing solutions at Facebook, said in a statement.

Facebook has denied giving companies access to information without user consent and rejected the idea that the new revelations constitute a violation of its privacy order with the U.S. Federal Trade Commission. A report by The New York Times claimed, based on an investigation of internal documents, that Facebook allowed Microsoft Corp.'s Bing search engine to see the names of many Facebook users' friends without approval.