A USGS (U.S. Geological Survey) geologist inspects a recent Lava flow from a Kilauea volcano fissure on Hawaii's Big Island on May 19, 2018 in Kapoho, Hawaii.

The Trump administration is tightening rules over media access to federal scientists in a move that represents a reversal from past practices, according to the Los Angeles Times.

The Times said one change applies to scientists who work at the U.S. Geological Survey, a federal science agency specializing in natural resources and natural hazards within the U.S. Department of the Interior. The change means scientists in many cases will no longer be able to talk directly to the media without first obtaining approval, including for news on climate change.

The paper spoke to unnamed USGS employees who said the policy was a shift from decades of past practices in dealing with the media and would likely end up giving the agency less overall exposure in commenting on scientific matters. USGS scientists are frequently called by reporters on deadline when large earthquakes are recorded by the agency.

"The clamp down on scientists at USGS comes in an environment of increasing control of scientific information by the federal government," Michael Halpern, deputy director of the Center for Science and Democracy at the Union of Concerned Scientists told CNBC. Based in Massachusetts, UCS is a nonprofit science advocacy organization.

Halpern added that last year the nation's health protection agency, the Centers for Disease Control and Prevention, notified its scientists that they needed to ask permission to respond to even basic requests for data. Also, he said public officials at the U.S. Environmental Protection Agency are "acting as gatekeepers and campaigners, not as facilitators of information flow."

According to Halpern, "This pattern reduces government accountability and robs states, journalists, and the public of access to scientific expertise. This is not the way a democracy should function."

The White House did not immediately return CNBC's request for comment.

Faith C. Vander Voort, deputy press secretary for the Interior, responded in an email that "the process and procedure of interview requests" is something that is guided by a department manual published in 2012.

As for the USGS, the Times said the directive means the agency's scientists specializing in everything from earthquakes, volcanoes and the effects of climate change will no longer be able to talk directly to the media without first obtaining approval. But a USGS spokesperson told CNBC on Friday that earthquakes, volcanoes and other events that involve public safety are "exempt."

The paper cited an April 25 email from the Interior's press secretary, Heather Swift. It that stated the standard protocol is that scientists must get approval for interviews with national media and even some regional outlets when the topics are considered "very controversial or ... likely to become a national story."

The Times said the Interior's communications office will be able to turn down interview requests.

"Department of Interior officials are within their rights to control communications about policy," said Halpern. "But controlling communications about science needlessly politicizes science and deprives the public of access to experts who are paid by their tax dollars. The default practice should be transparency and openness."

Halpern said the USGS and Interior's stated policies do not give political appointees the right to control what scientists share about their research and knowledge on science matters.

Indeed, an online USGS manual on news release and media relations policy states: "The USGS supports and encourages employees to speak on behalf of the USGS to news media representatives about their official work and freely and openly discuss scientific, scholarly, technical information, findings and conclusions based on their official, published work or area of expertise."

Read the full LA Times story here.