An independent IRS monitor announced Monday it will block the release of roughly 400 more pages of documents related to unauthorized leaks of confidential taxpayer information to the White House.

The Treasury Inspector General for Tax Administration (TIGTA) told the watchdog group Cause of Action it would be withholding nearly all of the 2,500 documents it located that were related to unauthorized IRS leaks to the White House. Earlier this month, TIGTA told Cause of Action it was withholding roughly 2,100 of the documents and said it would take an additional two weeks to review the rest.

TIGTA released 31 pages of documents on Monday to Cause of Action, 27 of which were already publicly available. Most were responses to letters from Republican senators.

As previously reported by the Washington Free Beacon, Cause of Action filed a Freedom of Information Act (FOIA) lawsuit against TIGTA for the long-sought-after records after the agency refused to even acknowledge whether they existed or not.

A federal judge ruled in September that TIGTA could not hide the existence of its investigations into improper leaks. In response TIGTA identified 2,509 responsive documents to Cause of Action’s FOIA request but said it was barred by law from releasing them.

TIGTA has used a statute meant to shield confidential taxpayer information to block FOIA requests over the past several years that seek information on investigations into politically motivated IRS leaks by the Obama administration.

For example, TIGTA refused to confirm or deny the existence of an investigation into former White House economic adviser Austan Goolsbee in response to several FOIA requests from the Washington Free Beacon, Koch Industries, and Cause of Action.

Goolsbee sparked a mini-scandal in 2010 when said during a background press briefing that Koch Industries—the company of libertarian philanthropists Charles and David Koch—paid no income taxes.

"It is disappointing that more than 4 years later, we still don't know what Mr. Goolsbee exactly did or what TIGTA's investigation revealed," Koch Industries general counsel Mark Holden said in a statement to the Free Beacon.

In a statement, Cause of Action said it will file a motion claiming TIGTA is violating public record law by refusing to release the rest of the records.

In response to a question about the case at a White House press briefing earlier this month, White House press secretary Josh Earnest said the Obama administration "has been very rigorous in following all of the rules and regulations that govern proper communications between treasury officials and White House officials and the Internal Revenue Service."