WASHINGTON (Reuters) - Republican U.S. presidential candidate Donald Trump has made "appalling" comments about Bowe Bergdahl and may be called as a witness in the Army sergeant's court-martial on a desertion charge, one of Bergdahl's lawyers said on Friday.

Eugene Fidell, a military law attorney at Yale Law School who is defending Bergdahl, said on CNN that Bergdahl's legal team has been monitoring statements by the front-runner for the Republican presidential nomination in November's election as possibly affecting his client's right to a fair trial.

Fidell said the defense team has compiled an eight-page log of "some of the various appalling comments that Mr. Trump has made in an effort to – it's like a lynch mob actually – to incite ill will and vilification of Sergeant Bergdahl."

Bergdahl is accused of abandoning his combat outpost in Afghanistan before being captured by the Taliban in 2009.

He spent five years as a Taliban prisoner before being released in a prisoner swap in 2014. Bergdahl, 29, was charged last year with desertion and endangering U.S. troops. The latter offense carries a possible life sentence.

Some fellow troops resented the military resources devoted to searching for him. Republicans criticized the Obama administration for the prisoner swap and Trump has become one of its most unforgiving critics, calling Bergdahl "a no-good traitor who should have been executed."

"There has been a pattern here that is so extensive that it has certainly raised in the mind of the defense team whether Sergeant Bergdahl's right to a fair trial has been irreparably compromised by Mr. Trump's comments," Fidell told CNN.

Fidell said Trump "may wind up facing a defamation case down the road," but said he has not made a final decision on calling the billionaire businessman as a witness in the court-martial. "We’d like to continue to monitor his comments,” Fidell added.

Reporting by Tim Ahmann; writing by Doina Chiacu.

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