DENVER — For years now, some veterans groups and marijuana advocates have argued that the therapeutic benefits of the drug can help soothe the psychological wounds of battle. But with only anecdotal evidence as support, their claims have yet to gain widespread acceptance in medical circles.

Now, however, researchers are seeking federal approval for what is believed to be the first study to examine the effects of marijuana on veterans with chronic post-traumatic stress disorder.

The proposal, from the Multidisciplinary Association for Psychedelic Studies in Santa Cruz, Calif., and a researcher at the University of Arizona College of Medicine, would look at the potential benefits of cannabis by examining 50 combat veterans who suffer from the condition and have not responded to other treatment.

“With so many veterans from the wars in Iraq and Afghanistan, there is a widely accepted need for a new treatment of PTSD,” said Rick Doblin, founder and executive director of the psychedelic studies group. “These are people whom we put in harm’s way, and we have a moral obligation to help them.”