SYDNEY, AUSTRALIA - A MAN was charged in an Australian court on Thursday with murdering a Chinese student who fell naked to her death from an apartment balcony in Sydney.

The 18-year-old was one of four Asian students - three girls and a man - who were allegedly sexually assaulted for up to an hour by a knife-wielding predator on Monday, before two of them fell from a balcony.

Her boyfriend, a 19-year-old Korean, remains in hospital after suffering serious spinal injuries and multiple broken bones when he fell - also naked - from the third-floor apartment.

Brendan Dennison, 26, was charged with a total of 21 offences including murder, breaking and entering, aggravated sexual assault and armed robbery.

Police said earlier it appeared the intruder forced his way into the apartment after holding a knife to the throat of one of the women as she was admitted through the building's security entrance.

The 18-year-old girl's mother arrived at Sydney airport on Thursday and was picked up by a police escort, the Australian Broadcasting Corporation reported.

A representative of the Chinese consulate told reporters outside the court that the woman's mother lost everything in the Sichuan earthquake earlier this year.

'She lost her business, she lost her home, now she's lost her only child,' Daniel Sheen told ABC.

Dennison, who was arrested on Wednesday night after police released closed circuit television footage showing a man near the apartment building, was remanded in custody and will face court again in December.