Racism in Australia.

A young Brisbane man has apologised and blamed alcohol for a shocking racist rant against a Queensland Rail security that went viral online.

A five minute video, filmed by a friend, shows the reported 17-year-old abusing a security guard during an altercation over why the commuter train had been stalled.

After being told the train would remain stopped until he got off, the teen loudly and repeatedly calls the security guard a 'n****r', a 'black c**t' and a 'black dog'.

"Do you want to come to Australia and learn some proper English?" he tells the guard.

"That is not the issue," replied the guard.

"Learn some f***ing English 'cause this is Australia... I can't understand you," retorted the teen.

The young male then turns on fellow passengers who began to protest his behaviour and demanded he exited the train.

He then challenged the guard and another passenger to a fight before eventually being convinced by his friend, who laughed throughout the entire incident, to leave the train before police arrive.

When the video went viral, a number of Australians expressed their outrage at the incident, labelling it 'disgusting', 'pathetic' and a 'disgrace'.

"What a tolerant man that security guard was to listen to that and not react and to make sure that he still stood between the instigator and other passengers," posted one Facebook user.

"I almost ALMOST stopped watching before the decent people stepped in. So glad I didn't have to watch this ugly Australian go unchallenged," said another.

By 11pm on Saturday, the offender had posted two separate updates on his Facebook in relation to the incident.

"I was just drunk couldn't remember s**t so stop over reacting, but I am proud to be white! OWS STAND STRONG!" it read.

The second post appeared more apologetic.

"I'm really sorry to everyone that was affected by the video I really can not remember anything out of all honesty the post made before was someone else I know this is no excuse."

"But can you all see from my point of view that I was a f***ing idiot and I'm really sorry."