Malcolm Turnbull's own department is attempting to bury an "urgent" review of offensive Wikipedia edits made by public servants.

And it is refusing to say what, if anything, its initial investigation found.

An investigation was ordered after Fairfax Media revealed thousands of anonymous edits of the free online encyclopaedia - which included insults to world leaders and a former prime minister, and even a claim that the Holocaust was "justified" - had potentially been made by public servants.

The chief of Mr Turnbull's Department of Prime Minister and Cabinet, Martin Parkinson, personally ordered the heads of the Defence, Foreign Affairs and Trade, Health, Agriculture and Parliamentary Services departments to "investigate as a matter of urgency" and report back within a week.