WASHINGTON (AP) — A leading House Republican warned the Obama administration on Thursday about demoting a federal worker who complained to her agency’s internal watchdog that political appointees were interfering with records requests by journalists and others.

Rep. Darrell Issa, chairman of the House Oversight and Government Reform Committee, said the demotion at the Department of Homeland Security “appeared to be an act of retaliation.” The committee is investigating the political reviews of records requests under the Freedom of Information Act.

“Obstructing a congressional investigation is a crime,” said Issa, R-Calif.

The department said it had done nothing wrong.

Issa urged Homeland Security Secretary Janet Napolitano to remind employees about their rights and whistle-blower protections, to make agency managers “aware of the consequences for retaliation against witnesses who furnish information to Congress.”

Issa accused the administration of improperly demoting Catherine Papoi, the former deputy unit chief in charge of the Freedom of Information Act. His charge raised the stakes in the broad congressional inquiry into President Barack Obama’s promises to improve government transparency.

The lawmaker said he will ask that Papoi be reinstated because he believes she was “demoted in violation of the spirit” of the whistle-blower law.

“Denying or interfering with employees’ rights to furnish information to Congress is against the law,” Issa wrote in a five-page letter to Napolitano that was obtained by The Associated Press. “Federal officials who retaliate against or otherwise interfere with employees who exercise their right to furnish information to Congress are not entitled to have their salaries paid by taxpayer dollars.”

The department said Papoi was not technically demoted because she never lost pay or benefits. Yet Papoi’s new boss, Delores J. Barber, took over Papoi’s title and moved into Papoi’s office. Papoi, who has a law degree, earns between $99,628 and $129,517. Under the federal employment system, a demotion usually involves loss of a pay grade.

Papoi, who applied for the new position awarded to Barber, is on leave. The department said a panel of career employees recommended Barber over Papoi. The political appointee whom Papoi accused of illegal behavior, chief privacy officer Mary Ellen Callahan, chose Barber for the job in December.

The department cited what it said were 11 factual inaccuracies by Issa and complained about “unfounded allegations of bad faith and a breach of legal ethics.”

“The department has not taken any retaliatory action against employees that have provided information to your committee,” Assistant Secretary Nelson Peacock said.

Issa disclosed in his letter that Papoi complained confidentially to the inspector general in March 2010 that the department, under a directive signed by Callahan, had illegally sidetracked hundreds of requests from journalists, watchdog groups and others for federal records to top political advisers. The advisers wanted information about those requesting the materials.

In some cases, the release of documents considered politically sensitive was delayed, according to more than 1,000 pages of e-mails subsequently obtained by the AP, which wrote about the practice last summer. The e-mails did not show political appointees stopping records from coming out. But they did show acute political sensitivities that slowed the process.

Career employees were ordered to provide political staff with information about the people who asked for records — such as where they lived and whether they were private citizens or reporters — and about the organizations where they worked. If a member of Congress sought documents, employees were told to specify Democrat or Republican.

The AP reported that the inspector general’s office had conducted interviews to determine whether political advisers acted improperly, but its findings have not been made public nearly one year after Papoi’s complaints.

“I knew full well I could be jeopardizing my career, but I have to be able to sleep at night,” Papoi told the AP in an interview.

At a Senate Judiciary Committee hearing this week, Sen. Charles Grassley, R-Iowa, said, “It would seem obvious that the political vetting process at the Department of Homeland Security that was uncovered by AP violates both the president’s and the attorney general’s orders.”

Grassley said he has asked inspectors general at dozens of executive branch agencies to investigate whether other parts of the administration are conducting similar political reviews.

A senior Justice Department official in charge of Obama’s openness policy, Melanie Pustay, told senators Tuesday that “if the statements in the (AP) article are true, it would be very serious, and we would have very serious concerns with that.”

Pustay said Justice Department rules make clear that the identity of the person requesting records shouldn’t affect whether the government provides information. She acknowledged that political appointees in the Justice Department are told about information requests “for awareness and management purposes, and that’s all.”