Three charged over Sydney teen's assault

Three people have been charged with sexually assaulting and robbing a 16-year-old girl in a carpark in southwest Sydney last month.

Police said the girl was in the forecourt of a library in Liverpool about 9.20pm on Saturday (AEST), June 21, when she was approached by a group of six males.

She walked with the group to a nearby carpark, where she was allegedly sexually assaulted in a stairwell, and her phone was stolen from her handbag.

The group left and the girl returned to the library, where she got help and police were contacted.

Police on Tuesday arrested two 16-year-old boys and a 20-year-old man following searches at homes in Warwick Farm, Cabramatta and Regents Park.

The man is due to appear in Liverpool Local Court on Wednesday, charged with robbery in company and two counts of aggravated sexual assault in company.

The teenagers will appear before a Children's Court, each charged with aggravated sexual assault in company and robbery in company.