LONDON - WikiLeaks' editor-in-chief claims his organization doesn't know who sent it some 91,000 secret US military documents, telling journalists that the website was set up to hide the source of its data from those who receive it.

Julian Assange didn't say whether he meant he had no idea who leaked the documents or whether his organization simply could not be sure. But he did say the added layer of secrecy helps protect the site's sources from spy agencies and hostile corporations.

"We never know the source of the leak," he told journalists gathered at London's Frontline Club late Tuesday. "Our whole system is designed such that we don't have to keep that secret."