WASHINGTON — Two scientists have resigned from an Environmental Protection Agency advisory board to protest agency Administrator Scott Pruitt’s removal of their colleagues.

Carlos Martín, a senior research associate at the Urban Institute’s Metropolitan Housing and Communities Policy Center, and Peter B. Meyer, president of the E.P. Systems Group, a Pennsylvania-based environmental analysis firm, said in a letter to EPA staff on Friday that it was “with certain regret and concern — and in protest” that they step down from a Board of Scientific Counselors subcommittee on sustainable and healthy communities. Martín posted the resignation letter to Twitter on Friday morning.

Pruitt this week dismissed half of the members of EPA’s 18-member /www.epa.gov/bosc"}}" data-beacon-parsed="true">Board of Scientific Counselors, which advises the agency’s Office of Research and Development on scientific research programs. Among those Pruitt booted were subcommittee co-chairs Courtney Flint and Robert Richardson, who Martín and Meyer described as “leading scholars.” Their removal came as a “shock” and “suggests that our collective knowledge is not valued by the current EPA administrators,” Martín and Meyer wrote.

“Like so many of our colleagues in the broader research community, we have deep concerns about the leadership at EPA and its continued obfuscation of scientific evidence and the research enterprise,” they said.

Just resigned from EPA subcommittee to protest removal of @ecotrope & Courtney Flint. Painful professional decision. #standupforscience pic.twitter.com/Zz09bD0vnj — Carlos Martín (@carlosonhousing) May 12, 2017

EPA’s decision not to re-appoint members of the internal review board has been viewed as another attack on science by a climate change-denying administrator who previously sued the agency he now leads more than a dozen times.

A spokesman for Pruitt told The New York Times this week the review board positions could be given to representatives from polluting industries the EPA is supposed to monitor, in an effort “to take as inclusive an approach to regulation as possible.”

“The administrator believes we should have people on this board who understand the impact of regulations on the regulated community,” the spokesman, J.P. Freire, said.

Shortly after receiving news that he would not be reappointed, Richardson, an ecological economist at Michigan State University, posted to Twitter that he had been “Trumped.” In an interview with CNN’s Brooke Baldwin, he said he saw the removals as a “political action.”

Martín and Meyer said in their letter that they are concerned about the Trump administration’s proposal to gut the EPA budget, and that they believed any replacements of Richardson and Flint would “similarly devalue” their work. The two said they “cannot in good conscience be complicit in our co-chairs’ removal, or in the watering down of credible science, engineering, and methodological rigor that is at the heart of that decision.”

The Board of Scientific Counselors is made up of scientists and engineers from academic institutions, environmental groups, industry and government. Supported by five separate subcommittees, it provides independent, expert advice to EPA’s main research arm on programs dealing with such issues as climate change, chemical safety and air quality.

Genna Reed, a science and policy analyst with the Union of Concerned Scientists, wrote in a blog post that the departures of Martín and Meyer are “further indication that the administration is inserting politics where it doesn’t belong and that scientists are unwilling to tolerate this blatant interference in what should be independent science advice.”

Liz Perera, the Sierra Club’s public health policy director, applauded the two scientists for “putting their feet down in the face of Trump and Pruitt’s complete and total disdain for science, reality and the very foundations of our government.”

Nick Visser contributed reporting.