Oklahoma Rep. Jim Bridenstine is asking what the Obama administration has to hide after he was denied access Monday to a Health and Human Services facility at Fort Sill currently housing up to 1,200 illegal immigrant children.

“There is no excuse for denying a Federal Representative from Oklahoma access to a federal facility in Oklahoma where unaccompanied children are being held,” the Republican said in a press release.

“After my visit today with the base commander, I approached the barracks where the children are housed,” he said. “A new fence has been erected by HHS, completely surrounding the barracks and covered with material to totally obscure the view. Every gate is chained closed.”

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An HHS official told Mr. Bridenstine that no visitors were allowed, and that he’d have to go through HHS legislative affairs to schedule a formal visit for July 21.

“Any Member of Congress should have the legal authority to visit a federal youth detention facility without waiting three weeks,” Mr. Bridenstine said in the release. “What are they trying to hide? Do they not want the children to speak with Members of Congress? As a Navy pilot, I have been involved in operations countering illicit human trafficking. I would like to know to whom these children are being released.”

Fort Sill, along with Lackland Air Force Base in San Antonio and Ventura County Naval Base in Oxnard, Calif., have been set up by HHS to house thousands of unaccompanied alien children (UAC) who were apprehended at the southern U.S. border.

HHS holds custody of the children until they are released to a so-called “sponsor” in the United States.