A key congressional committee on oversight is accusing the Department of Homeland Security of non-cooperation, witness tampering and even attempted theft of committee documents.

The 152-page report comes on the eve of hearings on transparency about DHS by the House Oversight and Government Reform Committee.

The accusations were met with a swift condemnation from a DHS spokesman, who accused Committee Chairman Darrell Issa, R-Calif., of reaching conclusions before the hearing got under way.‬

‪"While the Committee’s report spends a good deal of space making allegations of politicization and obstruction, the facts simply do not support these claims. Ironically, the report itself is full of selective omissions and redactions that appear to have been made to support these allegations,"‬ said DHS spokesman Amy Kudwa.

‪Kudwa also noted that the findings reach an entirely different conclusion than DHS's Inspector General did in a separate report.‬

‪The release coincided with Fox News obtaining an e-mail exchange written to and by political appointees at the agency.

The e-mails appear to suggest a resistance to releasing documents requested under the Freedom of Information Act.

In one e-mail, a career DHS FOIA specialist asks political appointees to search for documents pertaining to the BP oil spill "using a time frame of April 20th, 2010, to May 13, 2010."‬

‪When one employee asks, "What is my search term on this?" a third political appointee responds, "I used oil spill from 4/20 -4/30, when the request was sent in."‬

‪That response leaves unexamined a two-week period of e-mails that were sought in the original FOIA request.‬

‪Chairman Issa believes the e-mail exchange is but a small part of a larger pattern of intentional obfuscation by political appointees at DHS.‬

‪"We've found that there has been politicization of FOIA - that instead of documents flowing more quickly and with the bias being towards openness - there's been a tendency to evaluate everything in a political light," Issa said.

The chairman suggested there was a preoccupation in DHS with the political affiliations of those seeking FOIA requests. He said, "We haven't seen that since the Nixon Administration."‬

‪In addition, in other newly released e-mails, one career employee at the Department of Homeland Security used words such as "crazy and meddling" to describe the scrutiny of FOIA requests by political appointees. Another e-mail indicates there was "constant stonewalling" by department lawyers to open records requests.‬

‪Still, none of these released e-mails yet indicate that political appointees at DHS were hiding some "smoking gun" or some bombshell of malfeasance.

The obfuscation appears to have been committed in the interest of political super-sensitivity, not in the interest of protecting great secrets. Whether that changes may be revealed in Issa's hearings as they get under way Thursday morning.‬

‪In the midst of all the intense scrutiny, DHS officials maintain that the backlog of FOIA requests were largely left over from the Bush Administration. The say that under the Obama Administration, they have reduced the FOIA backlog by 84 percent and reduced the amount of time it takes to process FOIA requests from 240 days to 85 days.‬

Doug McKelway joined Fox News Channel (FNC) in November 2010 and serves as a Washington-based correspondent. Click here for more information on Doug McKelway