The federal government has suspended a wildlife biologist whose sightings of dead polar bears in Arctic waters became a rallying point for campaigners seeking to blunt the impact of global warming.

The Bureau of Ocean Energy Management, Regulation and Enforcement notified the biologist, Charles Monnett, on July 18 that he had been placed on administrative leave pending an internal investigation into “integrity issues,” according to a copy of a letter posted online by the watchdog group Public Employees for Environmental Responsibility.

Documents posted by the group indicate that the inquiry centers on a 2006 report that Dr. Monnett co-wrote on deaths among polar bears swimming in the Beaufort Sea.

Dr. Monnett and a co-author, Jeffrey Gleason, prepared the seven-page observational report for the peer-reviewed journal Polar Biology after spotting four dead polar bears during an aerial survey of bowhead whales in the Beaufort Sea in 2004. As word of the sightings spread, images of drowned polar bears became a staple for activists who warned that global warming and the retreat of sea ice were threatening the bears’ survival.