Queensland police are investigating a racist rant on a Brisbane train after a video emerged online.

Queensland police say the public should have confidence in the justice system after detectives charged two young men over a shocking racist attack on a Brisbane train.

A five minute video of the incident, which happened at the Indooroopilly train station in Brisbane's west on October 2, shows a young man abusing a security guard.

The confrontation appears to have begun after the young man was told to take his feet off the seat, but he responds with a shocking tirade of racially-charged insults, demanding the guard "learn some english".

Two men, a 17 year old from Brisbane and an 18 year old from Ipswich, have been charged over the incident.

Police attended the station after the train had left, assistant commissioner Alistair Dawson said.

"The severity of this matter was not known to police until late last night," he told reporters on Sunday.

The footage, apparently shot by an acquaintance of the abusive passenger who can be heard laughing, also shows other passengers reacting in disgust.

Mr Dawson praised other commuters who "selflessly" came to the defence of the guard and appealed for five witnesses who were on board the train to speak with police.

On Saturday night, an apology appeared on a Facebook account purporting to belong to the 17 year old, who claimed he could not remember the incident.

But his apology was deemed insufficient by premier Campbell Newman, who has spoken with the guard involved.

"I conveyed my absolute disgust at what he was subjected to," Mr Newman said.

"I told him how totally unacceptable it was."

Prime Minister Tony Abbott, who was in Brisbane on Sunday, echoed Mr Newman's comments.

"I absolutely deplore it," Mr Abbott told reporters.

"I think it's un-Australian."

Queensland's minister for Multicultural Affairs, Glen Elmes, called for the full force of the law to be brought down on the "drunken imbecile".

The young man's Facebook apology also prompted a flurry of replies, several threatening violence, after his name appeared in some media articles.

Mr Dawson said vigilantism was uncalled for.

"We need to allow the justice system to take effect. It is not about individuals taking it upon themselves to make judgment."

He said he had his own personal opinion about the conduct of the young man.

"But I sit before you today as a senior police officer, not as an individual."

Queensland Rail congratulated the contracted security guard and labelled the incident as "appalling".

The younger man has been charged with various offences including assault occasioning bodily harm.

The 18-year-old has been charged with creating a nuisance on a railway.

Both will appear in the Brisbane Magistrates Court on Monday.