The chief judge of the District’s federal court issued an unusual order Wednesday, apologizing to the public and the media for not making certain court documents widely available online.

The gesture of transparency by U.S. District Judge Royce C. Lamberth comes at a time when the Obama administration is under scrutiny for an unprecedented number of leak investigations, including one showing that the Justice Department had secretly probed the news-gathering activities of Fox News reporter James Rosen.

The investigation of Rosen was first reported Monday, after The Washington Post obtained court documents containing details of the case.

A federal judge had ordered the documents unsealed in November 2011, but they were kept sealed for 18 months and not posted on the court’s online docket until last week, after The Post inquired about them.

Lamberth blamed a series of administrative errors and said a review of the “performance of the personnel involved is underway.” He also said he was creating a new category on the court’s Web site where all search and arrest warrants will be made public unless they fall under a separate sealing order.

At issue were three 2010 search warrants issued as part of the Rosen probe.

The investigation centered on a former State Department arms expert, Stephen Jin-Woo Kim, who was indicted in 2010 for allegedly disclosing national defense information to Rosen, Fox’s chief Washington correspondent.

Rosen has not been prosecuted, but the Justice Department’s characterization of him in the search-warrant affidavit as a possible “co-conspirator” has alarmed civil libertarians as well as First Amendment watchdogs.