ASIO has swept in to secure classified documents after they were accidentally sold at a furniture auction.

In a stunning breach of national security revealed by the ABC this week, a trove of documents marked “top secret” and “AUSTEO” (Australian eyes only) were sold in locked filing cabinets for “small change” because they were heavy and the keys to unlock them were missing.

After a few months, their new owner attacked the locks with a drill, reports say, exposing secrets spanning the period from 2008 to 2013.

The revelations cover topics including NBN negotiations, the ill-fated Pink Batts scheme, Tony Abbott’s welfare plans, other documents lost by security agencies, and a multitude more.

It is similar to a Wikileaks cable dump, except the authorities did it to themselves.

ASIO officers delivered safes to the public broadcaster's Parliament House Bureau and South Bank studios around 1:00am on Thursday to secure the documents.

Lawyers for the ABC and the Department of Prime Minister and Cabinet (PM&C) are reportedly negotiating over what will happen next.