At least three federal agencies have hindered the oversight efforts of independent watchdogs by limiting their access to records, according to a complaint from more than half of the government’s inspectors general.

The officials, 47 of them, signed a letter to congressional oversight leaders on Tuesday saying the Justice Department, the Peace Corps and the Chemical Safety Board have withheld information on the basis that it was privileged.

The inspectors general, several of whom were nominated for their roles by President Obama, said such interpretations of the law represent “potentially serious challenges to the authority of every Inspector General and our ability to conduct our work thoroughly, independently, and in a timely manner.”

The Inspector General Act of 1978 ensures that inspectors general have “complete, unfiltered, and timely access to all information and materials … without unreasonable administrative burdens,” according to the letter.

The officials said that watchdogs from other agencies have “faced similar obstacles to their work, whether on a claim that some other law or principle trumped the clear mandate of the IG Act or by the agency’s imposition of unnecessarily burdensome administrative conditions on access.”

The letter was sent to Sens. Tom Carper (D-Del.) and Tom Coburn (R-Okla.), who head the Senate Homeland Security and Government Reform Committee, and Reps. Darrell Issa (R-Calif.) and Elijah Cummings (D-Md.), the top members of the House Oversight and Government Reform Committee.

“It is deeply troubling that federal agencies are increasingly obstructing this vital mission and, in doing so, undermining the very foundations of our government,” Coburn said in a statement. “This is an extremely dangerous place to be for a government established to be of the people, by the people, for the people.”

Carper said the letter “outlines serious concerns that are unacceptable.” He added that he will “continue to work closely with the Inspectors General to address their concerns.”

According to the letter, the Justice Department withheld records that its inspector general requested for three reviews, but the agency ultimately handed over the information based on a finding that the probes would assist its leaders.

Justice Department spokesman Brian Fallon disputed that narrative. “Because the documents at issue included grand jury material, credit reports, and other information whose dissemination is restricted by law, it was necessary to identify exceptions to those laws to accommodate the inspector general’s request,” he said. “But everything sought was provided.”

In the Peace Corps example, the agency withheld records of sexual assaults against its volunteers. The Peace Corps eventually allowed the information to be viewed under a special agreement, but it still has not allowed unfettered access.

“We are committed to working with the Inspector General to ensure rigorous oversight while protecting the confidentiality and privacy of volunteers who are sexually assaulted,” said Peace Corps spokeswoman Shira Kramer.

With the Chemical Safety Board, the agency argued that attorney-client privilege prevented it from providing access to certain documents related to a discrimination case. Coburn in June placed a hold on Obama’s nominees to the board because of the issue.

Chemical Safety Board spokeswoman Hilary Cohen said Tuesday that the agency was concerned that providing the requested materials would have waived attorney-client privilege and allowed others to obtain the information. “This could have harmed the agency and taxpayers in any future litigation of the matter,” she said.

Cohen added that “Congress could assist in these situations by clarifying that agency disclosures to an IG do not constitute a waiver of attorney-client privilege.”

Sen. Chuck Grassley (R-Iowa) agreed that legislation could help avoid similar clashes between agencies and their independent inspectors.

“This letter underscores the need for congressional review and possibly legislative action,” he said. “Congress needs to respond when inspectors general ask for help.”

Lawmakers have discussed drafting legislation this fall to address various concerns with access to information for inspectors general, although no specific proposals have emerged.