Ju Zhang, also known as Kelly, was last seen at her Epping home about 5.30pm last Monday and reported missing on Tuesday.

A 35-year-old man was arrested in Doncaster this afternoon and is assisting police with their enquiries.

Ms Zhang was wearing a pink pyjama top and shorts, and no shoes at the time of her disappearance.

She did not have any personal belongings with her at the time except her mobile phone.

Police have been concerned for Ms Zhang's welfare as she left her eight-year-old son alone. Her disappearance is extremely out of character.

"Kelly is a very loving mother to her son and would not leave him under any circumstances," Victoria Police Detective Inspector Andrew Stamper said.

Ms Zhang's son is understood to be in the care of her ex-husband's family.