Assange, who is currently fighting extradition to Sweden from the U.K., claimed on the Russian news channel that the social networking site was used by the U.S. government to spy on its citizens.
"Here we have the world's most comprehensive database about people -- their relationships, their names, their addresses, their locations and the communications with each other, their relatives -- all sitting within the United States, all accessible to U.S. intelligence," he said. "Facebook, Google, Yahoo -- all these major U.S. organizations have built-in interfaces for U.S. intelligence."
Assange added, "It's not a matter of serving a subpoena. They have an interface that they have developed for U.S. intelligence to use."
He also claimed that people using Facebook were helping U.S. intelligence operatives.
"Everyone should understand that when they add their friends to Facebook, they are doing free work for United States intelligence agencies in building this database for them."
Assange also addressed WikiLeaks' latest disclosures about Guantanamo Bay being used to incarcerate dozens of terrorists who admitted plotting attacks against the West.
"You know it has been a haven for terrorists, and it is certainly a haven for oligarchs and former regime dictators that have come here," he said.
A judge ruled in February that Assange should be extradited to Sweden where he is accused of sexually assaulting one Swedish woman and raping another during a visit to Stockholm last August.
Assange denied the accusations and said the charges were politically motivated.
He will appeal against a British judge's decision to extradite him to Sweden in a hearing at the High Court in London from July 12-13.