(QHA) -

The top U.S. intelligence official called on Wednesday for Edward Snowden and journalists who obtained documents the former contractor took without authorization from the National Security Agency to return the materials to authorities, Reuters reports.

At a hearing where the heads of five U.S. intelligence agencies ratcheted up rhetoric calling Snowden a "grave threat" to the nation, U.S. Director of National Intelligence James Clapper made comments that appeared to accuse journalists who wrote stories based on Snowden's leaks.

"Snowden claims he's won and that his mission is accomplished," Clapper testified at the U.S. Senate Intelligence Committee's annual hearing on global security threats.

"If that is so, I call on him and his accomplices to facilitate the return of the remaining stolen documents that have not yet been exposed to prevent even more danger to U.S. security," he said.

Snowden, who has accepted temporary asylum in Russia, has said that he gave journalists all the documents he took with him when he left his job as an NSA contractor in Hawaii.It is not clear how many documents Snowden downloaded.