Al Baldasaro
Veterans advocate Al Baldasaro, speaks to defend Republican US presidential nominee Donald Trump in Manhattan, New York on 31 May, 2016.Lucas Jackson/Reuters

An adviser to Republican GOP nominee Donald Trump has said Hillary Clinton should be "put in the firing line and shot for treason" over her handling of the Benghazi attack in which four Americans were killed.

The scathing remarks were made by New Hampshire state representative Al Baldasaro, who labelled the presumptive Democratic nominee "a piece of garbage." Baldasaro drew comparisons between Clinton and Jane Fonda, the US actress who visited Vietnam in 1972 to demonstrate against the war. The trip earned her the nickname "Hanoi Jane."

"I'm a veteran that went to Desert Shield, Desert Storm. I'm also a father who sent a son to war, to Iraq, as a Marine Corps helicopter avionics technician. Hillary Clinton, to me, is the Jane Fonda of the Vietnam," Baldasaro told the Jeff Kuhner Show.

"She is a disgrace for the lies that she told those mothers about their children that got killed over there in Benghazi. She dropped the ball on over 400 emails requesting back up security. Something's wrong there."

Baldasaro added: "This whole thing disgusts me, Hillary Clinton should be put in the firing line and shot for treason."

The retired Marine was contacted by the Boston Globe, but defended his remarks: "When you take classified information on a server that deals with where our State Department, Special Forces, CIA, whatever in other countries, that's a death sentence for those people if that information gets in the hands of other countries or the terrorists

"As far as I'm concerned, that's information for the enemy. In the military, shot, firing squad. So I stand by what I said."

He added: "Freedom of speech is a beautiful thing. I spoke my mind about how I feel. She's not above the law. Any other State Department employee or veteran did the same thing, they'd be in jail."

The US constitution defines treason as "levying war against them [the US], or in adhering to their enemies, giving them aid and comfort."