A US soldier who posted a photo on social media of soldiers smiling or striking poses around a flag-draped casket has been suspended.

The photo of the group of Wisconsin Army National Guard soldiers in combat uniforms was taken around an empty casket at a training centre in Arkansas.

A National Guard spokesperson said it had become aware of the posting on Monday.

The photo appeared on a social media site that belonged to Spc Terry Harrison, a member of the 1st Battalion, 147th Aviation Regiment.

A second photo on Ms Harrison's social media account suggested that the cold weather at a military funeral may result in a poor folding of the US flag to be presented.

Ms Harrison has been indefinitely suspended from the funeral honours detail pending an investigation into the matter.

Wisconsin National Guard's director of public affairs Maj Paul Rickert said he understood the content was upsetting to many.

"The Wisconsin National Guard expects all soldiers who carry out this sacred detail to handle it with professionalism and honour," he said.

"A military funeral is the final show of respect for our veterans and their families, and we take that solemn duty very seriously," Maj Rickert said.

The National Guard said it had taken measures to ensure the safety of the soldier following threats the soldier received via social media.