The Pentagon has said that the whistle-blower website WikiLeaks may be possessing more secret documents including files on Afghanistan and a video clip.

WikiLeaks is believed to have about 15,000 classified documents from the Afghan war, as many as 260,000 diplomatic cables and a video of casualties in Afghanistan, Pentagon spokesman Col Dave Lapan told reporters.

"We believe that WikiLeaks has in its possession additional documents that may be released in the future. They still have the 15,000 documents from Afghanistan. They still have a video from Afghanistan. Those are things they have talked about publicly," he said.

"And we have reason to believe they have other documents as well," Lapan said, adding that he has no further information on those.

The Department of Defence has publicly asked WikiLeaks to stop publishing these documents and return them.

However, WikiLeaks has gone ahead to publish these documents, which Pentagon says have endangered the lives of hundreds of its people in Afghanistan and Iraq.