As outrage builds over the the Trump administration’s policy of separating and detaining immigrant children and parents, the Department of Health and Human Services is telling members of Congress that they are prohibited from making unscheduled visits to the detention centers.

An e-mail from HHS, obtained by TPM, says lawmaker visits must be set up two weeks in advance, with no exceptions. When they are allowed to visit, members of Congress are not allowed to take any photos, record audio or speak with the detained children. They are not allowed to bring any staff members with them on the visit.

“To protect the privacy and vulnerability of children in its care, we cannot allow visitors to record or photograph anything within the facility property, nor are visitors allowed to interact with the children,” Sara Morse, the deputy assistant secretary for legislation at HHS, wrote to Capitol Hill offices. “We appreciate your cooperation.”

On a call with reporters on Wednesday, Rep. Raul Grijalva (D-AZ) railed against the policy.

“They’re making it so that Congress can’t perform oversight collectively or individually,” he said. “To not allow members of Congress the access they need to provide oversight and represent their constituents, that’s just institutional paranoia.”

These restrictions were communicated to Congress less than 24 hours after Sen. Bill Nelson (D-FL) and Rep. Debbie Wasserman Schultz (D-FL) were blocked from visiting a detention center in Homestead, Florida, where migrant children separated from the parents by the Trump administration are being held.

Told by HHS that he must request a visit two weeks in advance, Nelson told the AP: “I think what they’re doing is a cover-up for the president.”

Nelson’s office did not respond to TPM’s request for comment on the guidance the administration put out on Wednesday.

Sen. Jeff Merkley (D-OR), who was denied entry to a detention center in Texas in early June, has introduced a bill that would force the administration to allow members of Congress access to any facility with 24 hours notice. In a statement to TPM, he raised concern that the demand for two weeks of notice will allow the administration to hide atrocities or substandard conditions at the sites.

“This is an obvious ploy to prevent members of Congress from seeing these facilities as they truly operate on a day-to-day basis,” he said. “In order to conduct proper oversight, we need to see these facilities as they really are, not as they look after a two-week cleanup mission.”