The US Marine Corps once again did damage control after a photograph surfaced of a sniper team in Afghanistan posing in front of a flag with a logo resembling that of the Nazi SS - the special unit that murdered millions of Jews, gypsies and others.

The Corps said in a statement that using the symbol was not acceptable.

However, it was a naive mistake made by Marines who believed the SS symbol was meant to represent sniper scouts and never intended to associate themselves with a racist organisation, said Major Gabrielle Chapin, a spokeswoman at Camp Pendleton.

The Marines in the image will not be disciplined because investigators determined there was no malicious intent, Maj Chapin said.

Instead, the Corps used the incident as a training tool to talk to troops about what symbols are acceptable after it became aware of the photograph last November.

The image has since surfaced on an internet blog.

"I don't believe that the Marines involved would have ever used any type of symbol associated the Nazi Germany military criminal organisation that committed mass atrocities in WWII," Maj Chapin said. "It's not within who we are as Marines."

It was the second time this year the Marine Corps has had to do damage control for actions of its troops. It is also investigating a separate group of Marines recorded on video urinating on the dead bodies of Taliban fighters.

Mikey Weinstein of the Military Religious Freedom Foundation in Washington said he has been flooded with calls from former Marines offended by the photo and from one member of his organisation who is an Auschwitz concentration camp survivor. "This is a complete and total outrage," he said.

Mr Weinstein said his organisation was sending a letter seeking a full investigation to the head of the Marine Corps and Defence Secretary Leon Panetta. "First we have Marines peeing on dead bodies and now this," Mr Weinstein said.