House investigators are demanding that a nonpartisan environmental think tank in Washington hand over documents detailing its alleged relationship with China and other foreign entities.

The House Natural Resources Committee wants the World Resources Institute to provide the materials, some dating as far back as 2014, as part of its probe into possible attempts by foreign actors to influence U.S. environmental and natural resources policy via tax-exempt organizations, according to a letter the panel sent to WRI on Wednesday.

"The Committee is examining WRI's role in aiding China's perception management efforts with respect to pollution control and its international standing on environmental issues in ways that may be detrimental to the United States," the panel wrote.

"The Committee is concerned that WRI's relationship with the Chinese government may [influence] its political activities in the United States and may require compliance with FARA," the panel added, referring to the Foreign Agents Registration Act. That law requires any person or group acting as agents of foreign principals to disclose their interests.

In particular, Chairman Rob Bishop, R-Utah, and Rep. Bruce Westerman, R-Ark., noted that WRI praised China's Paris Agreement pledge to max out on greenhouse gas emissions by 2030 as "a serious and credible contribution." Some commentators, such as Oren Cass from the Manhattan Institute, have argued that the nation's commitment is merely tantamount to "business as usual."

"Conversely, WRI advocated for unrealistic Paris Agreement commitments by the United States in the face of sustained criticism that such commitments would cripple our country's economic competitiveness," the House Natural Resources Committee's letter says.

The note follows FBI Director Christopher Wray's July description of China as "the broadest, most challenging, most significant" counterintelligence threat to the U.S. Intelligence community reports indicate that China sometimes makes financial support and access to other resources like visas contingent upon academic institutions, think tanks, and nonprofit groups promoting pro-Chinese viewpoints.

A WRI spokesperson defended the body's 35-year record of using "independent, nonpartisan, and evidence-based" approaches to its advocacy of a range of global and development matters, saying it welcomed the opportunity to reply to the Committee's requests.

“In order to respond to the world’s most urgent sustainability challenges, it’s vital to work in the world’s developing countries and major economies, including China, the world’s most populous country," a spokesperson wrote in a statement to the Washington Examiner. "We are proud of our work in China, including on issues related to air pollution, traffic congestion, and water quality."

This is not the first time WRI has faced scrutiny over its relationship with China. Conservative free-market organizations sued the State Department in February 2017 for records sent between the department and Jennifer Morgan, the global director of WRI's Climate Program, relating to her role coordinating efforts "between green pressure groups and China to keep the climate gravy train chugging in the post-Obama world."

WRI has until Sept. 12 to produce the documents.

Editor's note: An earlier version of this article referred to the letter's co-signatory as Ranking Member Raul Grijalva, D-Ariz., as opposed to Rep. Westerman.