A 33-year-old South Korean student had his little finger chopped off and left arm broken in a brutal attack by a group of teenagers in Melbourne in late September.

Another 33-year-old South Korean man was assaulted in Sydney by a group of four or five people in October.

And on Sunday, a 27-year-old South Korean was punched in the head by two men trying to steal his mobile phone in Brisbane, the Yonhap news agency reported.

In the Melbourne attack, the victim, who gave his name as Mr Chang, approached the South Korean consulate in Melbourne for assistance this month after being dissatisfied by the police inquiries.

Victoria Police is continuing its investigations after the South Korean government requested they conduct a "more thorough and fair investigation", capture the perpetrators and compensate the victim.

The Foreign Ministry of South Korea also demanded Australia "come up with measures to prevent future incidents", the Korean broadcaster KBS reported earlier this month.

Korean media organisations have also labelled the initial investigation as "inadequate and unfair", and posed questions about police conduct and possible "cover-ups".

The victim, a Box Hill resident, has been studying at a Melbourne technical school since July on a six-month visa. The assault occurred at a park on Irving Street, Box Hill, at night.

The Korean newspaper Chosun Ilbo reported Mr Chang was approached by a group of teenagers who asked for a cigarette. When he refused, they assaulted him while shouting the words "f---ing Chinese".

Mr Chang blacked out during the attack and was taken to hospital, where his little finger was reattached.

The newspaper also said Mr Chang accused the police of "brushing off the assault simply as rowdy teenage behaviour" and "refused to inform him of the identities of the other teens". Mr Chang believes it was a racially motivated attack.

Fairfax Media can reveal a 14-year-old boy from Doncaster, Melbourne, was charged the day after the assault.

But last week, the news agency Yonhap reported that Victoria Police had replaced the original officers of the investigation team and offered an apology for the "insufficient initial probe".

Korean media reports have fuelled concerns about whether Australia was a safe destination for students and holidaymakers.

The Sydney attack victim, Mr Kim, told the Korea Herald he was struck with a golf club and ended up with skull fractures and two broken ribs.

In the Queensland incident, a man who gave his name as Mr Cho accused Queensland police officers of discrimination when reporting the attack.

"They made defamatory remarks, saying Asians are stupid and silly," he claimed.