UP TO a dozen soldiers have been caught up in Facebook slurs, which the brass say could lead to jail.

An immediate investigation has been launched into the Facebook posts by the Australian soldiers posted to Afghanistan.

Soldiers have been warned they could face a military tribunal, censure, discharge or even jail.

The soldiers are accused of describing Afghans as "ragheads", "dune coons", "sand niggaz" and "smelly locals" on Facebook.

In videos, photos and comments posted on the social networking site, some troops also allegedly mock those they have been sent to help.

A video posted on Facebook showing the bombing of a bridge was aired on Seven News last night.

When an Afghan bystander is frightened by the bomb, someone can be heard saying, "Scared the f... out of that muftee" and "f.....' boom".

Several soldiers list their employer as `F..... Ranga', some under their listing for Australian Defence Force.

The brother of one former Victorian soldier said last night his sibling was not a racist and he had joined the army to serve and protect.

"I have never found (him) to be a racist person," the brother said.

Defence said last night it had launched an investigation into reports of inappropriate and unacceptable material posted to social media by currently serving members of the Australian Army.

Acting Chief of Army Major General Paul Symon said the army was appalled.

"I struggle to understand, with all the training that we do and with the quality of soldiers that we have, that that sort of language has been posted," Maj-Gen Symon told Seven News.

He said thousands would be disgusted by the revelations of the behaviour.

"When you put words in the public domain, you will be held responsible," he said.

"What is happening here will cause deep offence to a lot of people."

One Facebook user wrote that he had just done an interview with the army and was waiting for a spot in the cavalry.

A soldier replied: "I'm in Afghan ... now. running over c.... yeeha." He later comments: "dune coons, sand niggaz. f... em all."

Australian Defence Association executive director Neil James said the revelations were "discharge stuff".

"Throw them out, they're not fit to be soldiers," he said.